MAXIM MAX7456 Technical data

MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
________________________________________________________________ Maxim Integrated Products 1
19-0576; Rev 0; 8/07
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
The MAX7456 single-channel monochrome on-screen display (OSD) generator lowers system cost by elimi­nating the need for an external video driver, sync sepa­rator, video switch, and EEPROM. The MAX7456 serves all national and international markets with 256 user-pro­grammable characters in NTSC and PAL standards. The MAX7456 easily displays information such as com­pany logo, custom graphics, time, and date with arbi­trary characters and sizes. The MAX7456 is preloaded with 256 characters and pictographs and can be repro­grammed in-circuit using the SPITMport.
The MAX7456 is available in a 28-pin TSSOP package and is fully specified over the extended (-40°C to +85°C) temperature range.
Applications
Security Switching Systems
Security Cameras
Industrial Applications
In-Cabin Entertainment
Consumer Electronics
Features
256 User-Defined Characters or Pictographs in
Integrated EEPROM
12 x 18 Pixel Character SizeBlinking, Inverse, and Background Control
Character Attributes
Selectable Brightness by RowDisplays Up to 16 Rows x 30 CharactersSag Compensation On Video-Driver OutputLOS, VSYNC, HSYNC, and Clock OutputsInternal Sync GeneratorNTSC and PAL CompatibleSPI-Compatible Serial InterfaceDelivered with Preprogrammed Character Set
Ordering Information
PART
PKG
CODE
MAX7456EUI+
English/
Japanese
U28E-5
*EP = Exposed pad. +Denotes a lead-free package.
Note: This device is specified over the -40°C to +85°C operat­ing temperature range.
Pin Configuration appears at end of data sheet.
SERIAL
INTERFACE
DISPLAY
ADDRESS
VIDEO DRIVER
VIDEO
TIMING
GENERATOR
DISPLAY MEMORY (SRAMS)
CHARACTER
ADDRESS
PIXEL CODE
SYNC
PIXEL
CONTROL
CHARACTER
MEMORY
(NVM)
OSD
GENERATOR
SAG
NETWORK
OSD MUX
DAC
SYSTEM
CLOCK
POR
SYNC
SEPARATOR
XTAL
OSCILLATOR
CLAMP
VIN
CLKIN
XFB
CLKOUT
RESET
HSYNC VSYNC
LOS
CS
SCLK
SDIN
SDOUT
AVDD
AGND
DVDD
DGND
PVDD
PGND
VOUT
SAG
MAX7456
Simplified Functional Diagram
SPI is a trademark of Motorola, Inc.
EVALUATION KIT
AVAILABLE
PIN-PACKAGE LANGUAGE
28 TSSOP-EP*
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
AVDD to AGND ........................................................-0.3V to +6V
DVDD to DGND ........................................................-0.3V to +6V
PVDD to PGND.........................................................-0.3V to +6V
AGND to DGND.....................................................-0.3V to +0.3V
AGND to PGND .....................................................-0.3V to +0.3V
DGND to PGND.....................................................-0.3V to +0.3V
VIN, VOUT, SAG to AGND......................-0.3V to (V
AVDD
+ 0.3V)
HSYNC, VSYNC, LOS to AGND ...............................-0.3V to +6V
RESET to AGND .....................................-0.3V to (V
AVDD
+ 0.3V)
CLKIN, CLKOUT, XFB to DGND ............-0.3V to (V
DVDD
+ 0.3V)
SDIN, SCLK, CS, SDOUT to DGND........-0.3V to (V
DVDD
+ 0.3V)
Maximum Continuous Current into V
OUT
........................±100mA
Continuous Power Dissipation (T
A
= +70°C)
28-Pin TSSOP (derate 27mW/°C above +70°C).......2162mW*
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(V
AVDD
= +4.75V to +5.25V, V
DVDD
= +4.75V to +5.25V, V
PVDD
= +4.75V to +5.25V, TA= T
MIN
to T
MAX
. Typical values are at V
AVDD
= V
DVDD
= V
PVDD
= +5V, TA= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
CONDITIONS MIN
UNITS
POWER SUPPLIES
Analog Supply Voltage V
AVDD
5 5.25 V
Digital Supply Voltage V
DVDD
5 5.25 V
Driver Supply Voltage V
PVDD
5 5.25 V
Analog Supply Current I
AVDD
VIN = 1V
P-P
(100% white flat field signal),
VOUT load, R
L
= 150
24 35 mA
Digital Supply Current I
DVDD
VIN = 1V
P-P
(100% white flat field signal),
VOUT load, R
L
= 150
25 30 mA
Driver Supply Current I
PVDD
VIN = 1V
P-P
(100% white flat field signal),
VOUT load, R
L
= 150
58 80 mA
NONVOLATILE MEMORY
Data Retention TA = +25°C 100 Years
Endurance TA = +25°C
Stores
DIGITAL INPUTS (CS, SDIN, RESET, SCLK)
Input High Voltage V
IH
2.0 V
Input Low Voltage V
IL
0.8 V
Input Hysteresis V
HYS
50 mV
Input Leakage Current VIN = 0 or V
DVDD
±10 µA
Input Capacitance C
IN
5pF
DIGITAL OUTPUTS (SDOUT, CLKOUT, VSYNC, HSYNC, LOS)
Output High Voltage V
OH
I
SOURCE
= 4mA (SDOUT, CLKOUT) 2.4 V
Output Low Voltage V
OL
I
SINK
= 4mA 0.45 V
Tri-State Leakage Current SDOUT, CS = V
DVDD
±10 µA
*As per JEDEC51 Standard (Multilayer Board).
SYMBOL
TYP MAX
4.75
4.75
4.75
100,000
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
AVDD
= +4.75V to +5.25V, V
DVDD
= +4.75V to +5.25V, V
PVDD
= +4.75V to +5.25V, TA= T
MIN
to T
MAX
. Typical values are at V
AVDD
= V
DVDD
= V
PVDD
= +5V, TA= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS MIN
TYP
MAX
UNITS
CLOCK INPUT (CLKIN)
Clock Frequency 27 MHz
Clock-Pulse High 14 ns
Clock-Pulse Low 14 ns
Input High Voltage
0.7 x V
Input Low Voltage
0.3 x V
Input Leakage Current VIN = 0V or V
DVDD
±50 µA
CLOCK OUTPUT (CLKOUT)
Duty Cycle 5pF and 10k to DGND 40 50 60 %
Rise Time 5pF and 10k to DGND 3 ns
Fall Time 5pF and 10k to DGND 3 ns
VIDEO CHARACTERISTICS
DC Power-Supply Rejection
V
AVDD
= V
DVDD
= V
PVDD
= 5V;
V
IN
= 1V
P-P
, measured at VOUT
40 dB
AC Power-Supply Rejection
V
AVDD
= V
DVDD
= V
PVDD
= 5V;
V
IN
= 1V
P-P
, measured at VOUT;
f = 5MHz; power-supply ripple = 0.2V
P-P
30 dB
Short-Circuit Current VOUT to PGND 230 mA
Line-Time Distortion LTD Figures 1a, 1b 0.5 %
Output Impedance Z
OUT
Figures 1a, 1b 0.2
Gain Figures 1a, 1b
2.0 2.11 V/V
Black Level At VOUT, Figures 1a, 1b
AGND
V
Input-Voltage Operating Range
V
IN
Figures 1a, 3 (Note 2) 0.5 1.2 V
P-P
Input-Voltage Sync Detection Range
V
INSD
Figures 1a, 3 (Note 3) 0.5 2.0 V
P-P
Maximum Output-Voltage Swing
V
OUT
Figures 1a, 1b 2.4 V
P-P
Output-Voltage Sync Tip Level 0.7 V
Large Signal Bandwidth (0.2dB)
BW V
OUT
= 2V
P-P
, Figures 1a, 1b 6 MHz
VIN to VOUT Delay 30 ns
Differential Gain DG 0.5 %
Differential Phase DP 0.5
Degrees
OSD White Level
VOUT 100% white level with respect to black level
1.45 V
Horizontal Pixel Jitter Between consecutive horizontal lines 24 ns
Video Clamp Settling Time 32 Lines
V
DVDD
1.89
V
DVDD
+ 1.5
1.25 1.33
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
4 _______________________________________________________________________________________
TIMING CHARACTERISTICS
(V
AVDD
= +4.75V to +5.25V, V
DVDD
= +4.75V to +5.25V, V
PVDD
= +4.75V to +5.25V, TA= T
MIN
to T
MAX
. Typical values are at V
AVDD
= V
DVDD
= V
PVDD
= +5V, TA= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
CONDITIONS MIN
UNITS
SPI TIMING
SCLK Period t
CP
100 ns
SCLK Pulse-Width High t
CH
40 ns
SCLK Pulse-Width Low t
CL
40 ns
CS Fall to SCLK Rise Setup t
CSS0
30 ns
CS Fall After SCLK Rise Hold t
CSH0
0ns
CS Rise to SCLK Setup t
CSS1
30 ns
CS Rise After SCLK Hold t
CSH1
0ns
CS Pulse-Width High t
CSW
100 ns
SDIN to SCLK Setup t
DS
30 ns
SDIN to SCLK Hold t
DH
0ns
SDOUT Valid Before SCLK t
DO1
20pF to ground 25 ns
SDOUT Valid After SCLK t
DO2
20pF to ground 0 ns
CS High to SDOUT High Impedance
t
DO3
20pF to ground 300 ns
CS Low to SDOUT Logic Level t
DO4
20pF to ground 20 ns
HSYNC, VSYNC, AND LOS TIMING
LOS, VSYNC, and HSYNC Valid before CLKOUT Rising Edge
t
DOV
20pF to ground 30 ns
NTSC external sync mode, Figure 4 375
VOUT Sync to VSYNC Falling Edge Delay
PAL external sync mode, Figure 6 400
ns
ELECTRICAL CHARACTERISTICS (continued)
(V
AVDD
= +4.75V to +5.25V, V
DVDD
= +4.75V to +5.25V, V
PVDD
= +4.75V to +5.25V, TA= T
MIN
to T
MAX
. Typical values are at V
AVDD
= V
DVDD
= V
PVDD
= +5V, TA= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS MIN
TYP
MAX
UNITS
OSD CHARACTERISTICS
OSD Rise Time
OSD insertion mux register OSDM[5,4,3] = 011b
60 ns
OSD Fall Time
OSD insertion mux register OSDM[5,4,3] = 011b
60 ns
OSD insertion mux register OSDM[2,1,0] = 011b
75 ns
OSD Insertion Mux Switch Time
SYMBOL
TYP MAX
t
VOUT-VSF
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
_______________________________________________________________________________________ 5
Note 1: See the standard test circuits of Figure 1. RL= 75, unless otherwise specified. All digital input signals are timed from a
voltage level of (V
IH
+ VIL) / 2. All parameters are tested at TA= +85°C and values through temperature range are guaran-
teed by design.
Note 2: The input-voltage operating range is the input range over which the output signal parameters are guaranteed (Figure 3). Note 3: The input-voltage sync detection range is the input composite video range over which an input sync signal is properly
detected and the OSD signal appears at VOUT. However, the output voltage specifications are not guaranteed for input sig­nals exceeding the maximum specified in the input operating voltage range (Figure 3).
TIMING CHARACTERISTICS (continued)
(V
AVDD
= +4.75V to +5.25V, V
DVDD
= +4.75V to +5.25V, V
PVDD
= +4.75V to +5.25V, TA= T
MIN
to T
MAX
. Typical values are at V
AVDD
= V
DVDD
= V
PVDD
= +5V, TA= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
CONDITIONS MIN
UNITS
NTSC external sync mode, Figure 4 400
VOUT Sync to VSYNC Rising Edge Delay
PAL external sync mode, Figure 6 425
ns
NTSC internal sync mode, Figure 5 40
VSYNC Falling Edge to VOUT Sync Delay
PAL internal sync mode, Figure 7 45
ns
NTSC internal sync mode, Figure 5 32
VSYNC Rising Edge to VOUT Sync Delay
PAL internal sync mode, Figure 7 30
ns
VOUT Sync to HSYNC Falling Edge Delay
NTSC and PAL external sync mode, Figure 8
310 ns
VOUT Sync to HSYNC Rising Edge Delay
NTSC and PAL external sync mode, Figure 8
325 ns
HSYNC Falling Edge to VOUT Sync Delay
NTSC and PAL internal sync mode, Figure 9
115 ns
HSYNC Rising Edge to VOUT Sync Delay
NTSC and PAL internal sync mode, Figure 9
115 ns
All Supplies High to CS Low t
PUD
Power-up delay 50 ms
NVM Write Busy t
NVW
12 ms
Figure 1. Standard Test Circuits
SYMBOL
t
VOUT-VSR
t
VSF-VOUT
t
VSR-VOUT
t
VOUT-HSF
t
VOUT-HSR
t
HSF-VOUT
t
HSR-VOUT
TYP MAX
SIGNAL
GEN
R
75
IN
C
IN
0.1µF
VIN
a) INPUT TEST CIRCUIT
MAX7456
VOUT
C
MAX7456
SAG
L
22pF
b) ONE STANDARD VIDEO LOAD, DC-COUPLED
R
L
150
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
6 _______________________________________________________________________________________
IMAGE WITH ON-SCREEN GRAPHICS
MAX7456 toc01
10µs/div
100% COLOR BARS RESPONSE
CVBS OUT (200mV/div)
MAX7456 toc02
75% COLOR BARS VECTOR DIAGRAM
CVBS OUT
MAX7456 toc03
10µs/div
60% MULTIBURST RESPONSE
CVBS OUT (200mV/div)
MAX7456 toc04
Typical Operating Characteristics
(V
AVDD
= +5V, V
DVDD
= +5V, V
PVDD
= +5V, TA= +25°C, unless otherwise noted. See the Typical Operating Circuit of Figure 2, if applicable.)
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
_______________________________________________________________________________________ 7
10µs/div
100% SWEEP RESPONSE
CVBS OUT (200mV/div)
MAX7456 toc05
DIFFERENTIAL PHASE
MAX7456 toc06
STEP
DIFFERENTIAL PHASE (deg)
6th5th4th3rd2nd1st
0
0.05
0.10
CVBS OUT
0.15
0.20
-0.05
DIFFERENTIAL GAIN
MAX7456 toc07
STEP
DIFFERENTIAL GAIN (%)
6th5th4th3rd2nd1st
0
0.05
0.10
0.15
0.20
-0.05
CVBS OUT
400ns/div
2T RESPONSE
CVBS IN (200mV/div)
CVBS OUT (200mV/div)
MAX7456 toc08
400ns/div
12.5T RESPONSE
CVBS IN (200mV/div)
CVBS OUT (200mV/div)
MAX7456 toc09
200ns/div
OSD OUTPUT 100% WHITE PIXEL
CVBS OUT (200mV/div)
MAX7456 toc10
Typical Operating Characteristics (continued)
(V
AVDD
= +5V, V
DVDD
= +5V, V
PVDD
= +5V, TA= +25°C, unless otherwise noted. See the Typical Operating Circuit of Figure 2, if applicable.)
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
8 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(V
AVDD
= +5V, V
DVDD
= +5V, V
PVDD
= +5V, TA= +25°C, unless otherwise noted. See the Typical Operating Circuit of Figure 2, if applicable.)
10µs/div
LINE-TIME DISTORTION
CVBS OUT (200mV/div)
MAX7456 toc11
2µs/div
H TIMING (EXTERNAL-SYNC MODE)
CVBS OUT (200mV/div)
MAX7456 toc12
2µs/div
H TIMING (INTERNAL-SYNC MODE)
CVBS OUT (200mV/div)
MAX7456 toc13
500µs/div
LOSS-OF-SYNC (LOW TO HIGH)
CVBS OUT (200mV/div)
LOS (1V/div)
MAX7456 toc14
500µs/div
LOSS-OF-SYNC (HIGH TO LOW)
CVBS OUT (200mV/div)
LOS (1V/div)
MAX7456 toc15
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
_______________________________________________________________________________________ 9
Pin Description
PIN NAME FUNCTION
1, 2, 13–16,
27, 28
N.C. No Connection. Not internally connected.
3 DVDD Digital Power-Supply Input. Bypass to DGND with a 0.1µF capacitor.
4 DGND Digital Ground
5 CLKIN
Crystal Connection 1. Connect a parallel resonant, fundamental mode crystal between CLKIN and XFB for use as a crystal oscillator, or drive CLKIN directly with a 27MHz system reference clock.
6 XFB
Crystal Connection 2. Connect a parallel resonant, fundamental mode crystal between CLKIN and XFB for use as a crystal oscillator, or leave XFB unconnected when driving CLKIN with a 27MHz system reference clock.
7
Clock Output. 27MHz logic-level output system clock.
8 CS Active-Low Chip-Select Input. SDOUT goes high impedance when CS is high.
9 SDIN Serial Data Input. Data is clocked in at rising edge of SCLK.
10 SCLK
Serial Clock Input. Clocks data into SDIN and out of SDOUT. Duty cycle must be between 40% and 60%.
11
Serial Data Output. Data is clocked out at the falling edge of SCLK. High impedance when CS is high.
12 LOS
Loss-of-Sync Output (Open-Drain). LOS goes high when the VIN sync pulse is lost for 32 consecutive lines. LOS goes low when 32 consecutive valid sync pulses are received. Connect to a 1k pullup resistor to DVDD or another positive supply voltage suitable for the receiving device.
17
Vertical Sync Output (Open-Drain). VSYNC goes low following the video input’s vertical sync interval. VSYNC is either recovered from VIN or internally generated when in internal sync mode. Connect to a 1k pullup resistor to DVDD or another positive supply voltage suitable for the receiving device.
18
Horizontal Sync Output (Open-Drain). HSYNC goes low following the video input’s horizontal sync interval. HSYNC is either recovered from VIN or internally generated when in internal sync mode. Connect to a 1k pullup resistor to DVDD or another positive supply voltage suitable for the receiving device.
19
System Reset Input. The minimum RESET pulse width is 50ms. All SPI registers are reset to their default values after 100µs following the rising edge of RESET. These registers are not accessible for reading or writing during that time. The display memory is reset to its default value of 00H in all locations after 20µs following the rising edge of RESET.
20 AGND Analog Ground
21 AVDD Analog Power-Supply Input. Bypass to AGND with a 0.1µF capacitor.
22 VIN PAL or NTSC CVBS Video Input
23 PGND Driver Ground. Connect to AGND at a single point.
24 PVDD Driver Power-Supply Input. Bypass to PGND with a 0.1µF capacitor.
25 SAG Sag Correction Input. Connect to VOUT if not used. See Figure 1b.
26 VOUT Video Output
—EP
Exposed Pad. Internally connected to AGND. Connect EP to the AGND plane for improved heat dissipation. Do not use EP as the only ground connection.
CLKOUT
SDOUT
VSYNC
HSYNC
RESET
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
10 ______________________________________________________________________________________
Detailed Description
The MAX7456 single-channel monochrome on-screen display (OSD) generator integrates all the functions need­ed to generate a user-defined OSD and insert it into the output signal. The MAX7456 accepts a composite NTSC or PAL video signal. The device includes an input clamp, sync separator, video timing generator, OSD insertion mux, nonvolatile character memory, display memory, OSD generator, crystal oscillator, an SPI-compatible inter­face to read/write the OSD data, and a video driver (see the Simplified Functional Diagram). Additionally, the MAX7456 provides vertical sync (VSYNC), horizontal sync (HSYNC), and loss-of sync (LOS) outputs for system synchronization. A clock output signal (CLKOUT) allows daisy-chaining of multiple devices.
See the MAX7456 Register Description section for an explanation of register notation use in this data sheet.
The 256 user-defined 12 x 18 pixel character set comes preloaded and is combined with the input video stream to generate a CVBS signal with OSD video out­put. A maximum of 256 12 x 18 pixel characters can be reprogrammed in the NVM. In NTSC mode, 13 rows x 30 characters are displayed. In PAL mode, 16 rows x 30 characters are displayed. When the input video sig­nal is absent, the OSD image can still be displayed by using the MAX7456’s internal video timing generator.
Video Input
The MAX7456 accepts standard NTSC or PAL CVBS signals at VIN. The video signal input must be AC-cou­pled with a 0.1µF capacitor and is internally clamped. An input coupling capacitance of 0.1µF is required to guarantee the specified line-time distortion (LTD) and video clamp settling time. The video clamp settling time changes proportionally to the input coupling capaci­tance, and LTD changes inversely proportional to the capacitance.
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
MAX7456
SDIN
+5V
27MHz
SDOUT
+5V
CVBS OUT
SAG
PGND
RESET
HSYNC
VSYNC
DGND
CLKIN
XFB
CLKOUT
CS
SDIN
SCLK
SDOUT
LOS
N.C.
SCLK
CS
CVBS IN
LOS
VS
HS
N.C.
N.C.
N.C.
CLKOUT
N.C.
N.C.
AGND
N.C.
N.C.
+5V
0.1µF
C
OUT
75
75
1k1k1k
0.1µF
0.1µF
0.1µF
C
SAG
DVDD
VOUT
PVDD
VIN
AVDD
Figure 2. Typical Operating Circuit
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 11
Input Clamp
The MAX7456’s clamp is a DC-restore circuit that uses the input coupling capacitor to correct any DC shift of the input signal, on a line-by-line basis, such that the sync tip at VIN is approximately 550mV. This establish­es a DC level at VIN suitable for the on-chip sync detection and video processing functions. This circuitry also removes low-frequency noise such as 60Hz hum or other additive low-frequency noise.
Sync Separator
The sync separator detects the composite sync pulses on the video input and extracts the timing information to generate HSYNC and VSYNC. It is also used for inter­nal OSD synchronization and loss-of-sync (LOS) detec­tion. LOS goes high if no sync signal is detected at VIN for 32 consecutive lines, and goes low if 32 consecu­tive horizontal sync signals are detected. During a LOS condition, when VM0[5] = 0 (Video Mode 0 register, bit
5), only the OSD appears at the VOUT. At this time, the input image is set to a gray level at VOUT as deter­mined by VM1[6:4]. The behavior of all sync modes is shown in Table 1.
COLOR BURST
SYNC TIP
LEVEL
BLACK LEVEL
WHITE LEVEL
MAXIMUM VIDEO SWING
INPUT VOLTAGE
MINIMUM VIDEO SWING
VIN
Figure 3. Definition of Terms
VIDEO MODE VIN VSYNC HSYNC LOS VOUT
Video Active Active Low VIN + OSD
Auto Sync Select Mode
VM0[5, 4] = 0x
No input Active Active High OSD only
Video Active Active Low VIN + OSD
External Sync Select
VM0[5, 4] = 10
No input Inactive (high) Inactive (high) High DC
Video Active Active High OSD only
Internal Sync Select
VM0[5, 4] = 11
No input Active Active High OSD only
Table 1. Video Sync Modes
X = Don’t care.
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
12 ______________________________________________________________________________________
Video Timing Generator
The video timing generator is a digital circuit generat­ing all internal and external (VSYNC and HSYNC) tim­ing signals. VSYNC and HSYNC can be synchronized to VIN, or run independently of any input when in inter­nal sync mode. The video timing generator can gener­ate NTSC or PAL timing using the same 27MHz crystal (see Figures 4–9).
Crystal Oscillator
The internal crystal oscillator generates the system clock used by the video timing generator. The oscillator uses a 27MHz crystal or can be driven by an external 27MHz TTL clock at CLKIN. For external clock mode, connect the 27MHz TTL input clock to CLKIN and leave XFB unconnected.
Display Memory (SRAM)
The display memory stores 480 character addresses that point to the characters stored in the NVM character memory. The content of the display memory is user­programmable through the SPI-compatible serial inter­face. The display-memory address corresponds to a fixed location on a monitor (see Figure 10). Momentary breakup of the OSD image can be prevented by writing to the display memory during the vertical blanking inter­val. This can be achieved by using VSYNC as an inter­rupt to the host processor to initiate writing to the display memory.
t
VOUT-VSF
1/2H
VERTICAL SYNCHRONIZATION
PULSE INTERVAL
VOUT
(ODD FIELD)
VOUT
(EVEN FIELD)
VSYNC
HSYNC
(ODD FIELD)
HSYNC
(EVEN FIELD)
50%
50%
t
VOUT-VSR
50%
50%
50%
Figure 4. VOUT,
VSYNC
, and
HSYNC
Timing (NTSC, External Sync Mode)
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 13
t
VSF-VOUT
1/2H
VERTICAL SYNCHRONIZATION
PULSE INTERVAL
VOUT
(ODD FIELD)
VOUT
(EVEN FIELD)
VSYNC
HSYNC
(ODD FIELD)
HSYNC
(EVEN FIELD)
50%
50%
t
VSR-VOUT
50%
50%
50%
50%
Figure 5. VOUT,
VSYNC
, and
HSYNC
Timing (NTSC, Internal Sync Mode)
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
14 ______________________________________________________________________________________
t
VOUT-VSF
t
VOUT-VSR
1/2H
VERTICAL SYNCHRONIZATION
PULSE INTERVAL
VOUT
(ODD FIELD)
VOUT
(EVEN FIELD)
VSYNC
HSYNC
(ODD FIELD)
HSYNC
(EVEN FIELD)
50%
50%
50% 50%
50%
50%
Figure 6. VOUT,
VSYNC
, and
HSYNC
Timing (PAL, External Sync Mode)
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 15
t
VSF-VOUT
t
VSR-VOUT
1/2H
VERTICAL SYNCHRONIZATION
PULSE INTERVAL
VOUT
(ODD FIELD)
VOUT
(EVEN FIELD)
VSYNC
HSYNC
(ODD FIELD)
HSYNC
(EVEN FIELD)
50%
50%
50% 50%
50%
50%
Figure 7. VOUT,
VSYNC
, and
HSYNC
Timing (PAL, Internal Sync Mode)
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
16 ______________________________________________________________________________________
VOUT
HSYNC
t
VOUT-HSF
t
VOUT-HSR
50%50%
Figure 8. VOUT, and
HSYNC
Horizontal Sync Timing (NTSC and PAL, External Sync Mode)
VOUT
HSYNC
t
HSF-VOUT
t
HSR-VOUT
50%
50%
Figure 9. VOUT and
HSYNC
Horizontal Sync Timing (NTSC and PAL, Internal Sync Mode)
Character Memory (NVM)
The character memory is a 256-row x 64-byte wide nonvolatile memory (NVM) that stores the characters or graphic images, and is factory preloaded with the char­acters shown in Figure 12. The content of the character memory is user-programmable through the SPI-com­patible serial interface. Each row contains the descrip­tion of a single OSD character. Each character consists of 12 horizontal x 18 vertical pixels where each pixel is represented by 2 bits of data having three states: white, black, or transparent. Thus, each character requires 54 bytes of pixel data (Figure 11).
The NVM requires reading and writing a whole charac­ter (64 bytes) at a time. This is enabled by an additional
row of memory called the shadow RAM. The 64-byte temporary shadow RAM contains all the pixel data of a selected character (CMAH[7:0]) and is used as a buffer for read and write operations to the NVM (Figure 13). Accessing the NVM is always through the shadow RAM, and is thus a two-step process. To write a char­acter to the NVM, the user first fills the shadow RAM using 54 8-bit SPI write operations, and then executes a single shadow RAM write command. Similarly, read­ing a character’s pixel values requires first reading a character’s pixel data into the shadow RAM, and then reading the desired pixel data from the shadow RAM to the SPI port.
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 17
DISPLAY MEMORY
(TWO, 256 x 16-BIT SRAMs)
0
ADDRESS (8 BIT)
L B C
L B C
B L K
B L K
I N V
I N V
L B C
B L K
I N V
479
29
DISPLAY AREA
(16 ROWS x 30 CHARACTERS)
0
29
450 479
CHARACTER ATTRIBUTE BIT DEFINITIONS: LBC = LOCAL BACKGROUND CONTROL BLK = BLINK CONTROL INV = INVERT CONTROL X = DON'T CARE
CHARACTER MEMORY
ADDRESS LOW (CMAL)
0
PIXEL DATA ARRANGEMENT IN CHARACTER MEMORY (NVM)
256 ROWS x 64 BYTES EEPROM
0 1 2 515253 6162 63
012
51 52 53 61 62 63
12 PIXELS
4 PIXEL VALUES
(1 BYTE)
(SEE FIGURE 11 FOR PIXEL MAP)
CHARACTER
DATA USAGE
(12 x 18 PIXELS)
012
51 52 53
18 PIXELS
2-BIT PIXEL DEFINITIONS: 00 = BLACK, OPAQUE 10 = WHITE, OPAQUE X1 = TRANSPARENT (EXTERNAL SYNC MODE) OR GRAY (INTERNAL SYNC MODE)
DISPLAY MEMORY ADDRESS (DMAH, DMAL)
DISPLAY MEMORY ADDRESS (DMAH, DMAL)
ADDRESS (8 BIT)
ADDRESS (8 BIT)
30
59
UNUSED
MEMORY
X
XXXX
X
XXXX
X
XXXX
CHARACTER
ADDRESS (CA)
CHARACTER
ATTRIBUTE
255
0
54
54
53
54
CHARACTER
DATA
CHARACTER MEMORY
ADDRESS HIGH (CMAH)
CHARACTER DATA ARRANGEMENT IN DISPLAY MEMORY (SRAM) 480 ROWS x 2 BYTES SRAM
63
Figure 10. Definitions of Various Parameters
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
18 ______________________________________________________________________________________
0 0, 1, 2
1 3, 4, 5
2 6, 7, 8
3 9, 10, 11
4 12, 13, 14
5 15, 16, 17
6 18, 19, 20
7 21, 22, 23
8 24, 25, 26
9 27, 28, 29
10 30, 31, 32
11 33, 34, 35
12 36, 37, 38
13 39, 40, 41
14 42, 43, 44
15 45, 46, 47
16 48, 49, 50
17 51, 52, 53
00 = BLACK
CHARACTER MEMORY
ADDRESS LOW
CMAL[5:0]
2-BIT PIXEL DEFINITION:
[5, 4] [3, 2]
10 = WHITE
X = DON'T CARE
X1 = TRANSPARENT (EXTERNAL SYNC MODE)
OR GRAY (INTERNAL SYNC MODE)
[x, y]
[x, y]
7
[7, 6] [5, 4] [3, 2]
[7, 6] [5, 4]
[7, 6]
[x, y]
PIXEL COLUMN NUMBER
PIXEL ROW NUMBER
[1, 0][5, 4] [3, 2]
[1, 0] [7, 6]
0
CDMI
[5, 4]
CDMI
[3, 2]
123456
CDMI
[7, 6]
CDMI
[1, 0]
[7, 6]
8 9 10 11
[5, 4] [3, 2]
[7, 6] [5, 4] [3, 2]
[7, 6] [5, 4] [3, 2]
[7, 6] [5, 4] [3, 2] [1, 0]
[7, 6] [5, 4] [3, 2] [1, 0]
[5, 4] [3, 2] [1, 0]
[1, 0]
[5, 4] [3, 2] [1, 0][7, 6]
[1, 0] [7, 6] [5, 4] [3, 2] [1, 0] [7, 6]
[7, 6] [5, 4]
[7, 6] [5, 4] [3, 2]
[7, 6] [5, 4] [3, 2] [1, 0]
[1, 0]
[3, 2] [1, 0] [7, 6] [5, 4]
[7, 6] [5, 4] [3, 2] [1, 0][7, 6] [5, 4] [3, 2] [1, 0]
[5, 4] [3, 2] [1, 0]
[1, 0][5, 4] [3, 2]
[1, 0]
[7, 6] [5, 4] [3, 2] [1, 0] [7, 6] [5, 4]
[7, 6] [5, 4]
[3, 2] [1, 0] [7, 6] [5, 4]
[1, 0] [3, 2] [1, 0]
[7, 6] [5, 4] [3, 2] [1, 0] [7, 6] [5, 4] [3, 2] [1, 0]
[5, 4] [3, 2] [1, 0]
[1, 0] [7, 6] [5, 4] [3, 2] [1, 0] [7, 6] [5, 4] [3, 2] [1, 0]
[7, 6] [5, 4] [3, 2] [1, 0] [7, 6] [5, 4] [3, 2] [1, 0]
[1, 0] [5, 4] [3, 2] [1, 0][7, 6] [7, 6]
[7, 6] [5, 4] [3, 2] [1, 0] [7, 6] [5, 4] [3, 2] [1, 0] [7, 6] [5, 4] [3, 2] [1, 0]
[7, 6] [5, 4] [3, 2] [1, 0]
[1, 0]
[7, 6] [5, 4]
[3, 2]
[7, 6] [5, 4] [3, 2]
[5, 4] [3, 2]
[5, 4]
[3, 2] [1, 0] [7, 6]
[7, 6] [5, 4] [3, 2] [1, 0]
[1, 0]
[1, 0]
[3, 2] [1, 0] [7, 6] [5, 4] [3, 2] [1, 0]
[1, 0] [7, 6][7, 6] [5, 4] [3, 2]
[7, 6][7, 6] [5, 4] [3, 2] [1, 0]
[3, 2]
[5, 4] [3, 2]
[1, 0]
[1, 0]
[7, 6] [5, 4] [3, 2] [1, 0] [7, 6] [5, 4] [3, 2] [1, 0]
[7, 6] [5, 4] [3, 2]
[7, 6]
[7, 6]
[5, 4] [3, 2] [1, 0] [7, 6] [5, 4] [3, 2] [1, 0] [7, 6]
[3, 2] [1, 0]
[7, 6] [5, 4] [3, 2] [1, 0] [7, 6] [5, 4] [3, 2]
[3, 2] [1, 0] [7, 6] [5, 4]
Figure 11. Character Data Usage (Pixel Map)
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 19
CA[3:0], CMAH[3:0]
CA[7:4], CMAH[7:4]
Figure 12. Character Address Map (Default Character Set)
MAX7456
On-Screen Display (OSD) Generator
The OSD generator sets each pixel amplitude based on the content of the character memory and Row Brightness registers (RB0–RB15).
OSD Insertion Mux
The OSD insertion mux selects between an OSD pixel and the input video signal. The OSD image sharpness is controlled by the OSD Rise and Fall Time bits, and the OSD Insertion Mux Switching Time bits, found in the OSD Insertion Mux (OSDM) register. This register con­trols the trade-off between OSD image sharpness and crosscolor/crossluma artifacts. Lower time settings pro­duce sharper pixels, but potentially greater crosscol­or/crossluma artifacts. The optimum setting depends on the requirements of the application and, therefore, can be set by the user.
Video-Driver Output
The MAX7456 includes a video-driver output with a gain of 2. The driver has a maximum of 2.4V
P-P
output swing and a 6MHz large signal bandwidth (0.2dB attenuation). The driver output is capable of driving two 150standard video loads.
Sag Correction
Sag correction is a means of reducing the electrical and physical size of the output coupling capacitor while achieving acceptable line-time distortion. Sag correc­tion refers to the low frequency compensation of the highpass filter formed by the 150Ω load of a back-ter- minated coaxial cable and the output coupling capaci­tor. This breakpoint must be low enough in frequency to pass the vertical sync interval (< 25Hz for PAL and < 30Hz for NTSC) to avoid field tilt. Traditionally, the breakpoint is made < 5Hz, and the coupling capacitor
must be very large, typically > 330µF. The MAX7456 reduces the value of this capacitor, replacing it with two smaller capacitors (C
OUT
and C
SAG
), substantially reducing the size and cost of the coupling capacitors while achieving acceptable line-time distortion (Table 2). Connect SAG to VOUT if not used.
Serial Interface
The SPI-compatible serial interface programs the oper­ating modes and OSD data. Read capability permits write verification and reading the Status (STAT), Display Memory Data Out (DMDO), and Character Memory Data Out (CMDO) registers.
Read and Write Operations
The MAX7456 supports interface clocks (SCLK) up to 10MHz. Figure 15 illustrates writing data and Figure 16 illustrates reading data from the MAX7456. Bring CS low to enable the serial interface. Data is clocked in at SDIN on the rising edge of SCLK. When CS transitions high, data is latched into the input register. If CS goes high in the middle of a transmission, the sequence is aborted (i.e., data does not get written into the regis­ters). After CS is brought low, the device waits for the first byte to be clocked into SDIN to identify the type of data transfer being executed.
The SPI commands are 16 bits long with the 8 most sig­nificant bits (MSBs) representing the register address and the 8 least significant bits (LSBs) representing the data (Figures 15 and 16). There are two exceptions to this arrangement:
1) Auto-increment write mode used for display memory
access is a single 8-bit operation (Figure 21). When performing the auto-increment write for the display memory, the 8-bit address is internally generated, and only 8-bit data is required at the serial interface.
2) Reading character data from the display memory,
when in 16-bit operation mode, is a 24-bit operation (8-bit address plus 16-bit data). See Figure 20.
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
20 ______________________________________________________________________________________
0
. . . . . . . . . . .
ADDRESS
DECODER
NVM ARRAY
(256 ROWS x 64 BYTES)
64-BYTE SHADOW RAM
CMAH [7:0]
CMDI [7:0] CMDO [7:0]
630
. . . . . . . . . . . . . . . . . . . . . . .
255
CMAL [5:0]
Figure 13. NVM Structure
C
OUT
(µF) C
SAG
(µF)
LINE-TIME DISTORTION
(% typ)
470 0.2
100 0.4
100 22 0.3
47 47 0.3
22 22 0.4
10 10 0.6
Table 2. SAG-Correction Capacitor Values
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 21
t
CSH0
t
CSS0
t
DH
t
CH
t
CL
t
CSS1
t
CSH1
t
CSW
t
CP
CS
SCLK
SDIN
SDOUT
t
DO1
t
DO2
t
DO3
t
DO4
t
DS
Figure 14. Detailed Serial-Interface Timing
CS
SCLK
SDIN
MSB LSB
12345678
9
10
11 121314 15 16
D7
D6
D5
D4
D3
D2
D1 D0
A6
A5
A4
A3A2A1 A0
0
Figure 15. Write Operation
CS
SCLK
SDIN
MSB
MSB
12345678
9
10
11 121314 15 16
D7
D6
D5
D4
D3
D2
D1 D0
X
A6
A5
A4
A3A2A1 A0
1
SDOUT
LSB
LSB
Figure 16. Read Operation
CS
SCLK
SDIN
MSB LSB
12345678
9
10
11 121314 15 16
00000111
L B C
B L K
I
N
V
00000
Figure 17. Writing Character Attribute Byte in 8-Bit Operation Mode
CS
SCLK
SDIN
MSB
MSB
12345678
9
10
11 121314 15 16
L B C
B L K
I
N
V
00000
X
1011XXXX
SDOUT
LSB
LSB
Figure 18. Reading Character Attribute Byte in 8-Bit Operation Mode
MAX7456
Resets
Power-On Reset
The MAX7456’s power-on reset circuitry (POR) pro­vides an internal reset signal that is active after the sup­ply voltage has stabilized. The internal reset signal resets all registers to their default values and clears the display memory. The register reset process requires 100µs, and to avoid unexpected results, read/write activity is not allowed during this interval. The display memory is reset, and the OSD is enabled typically 50ms after the supply voltage has stabilized and a sta­ble 27MHz clock is available. The user should avoid SPI operations during this time to avoid unexpected results. After 50ms (typical), STAT[6] can be polled to verify that the reset sequence is complete (Figure 22).
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
22 ______________________________________________________________________________________
CS
SCLK
SDIN
MSB LSB
12345678
9
10
11 121314 15 16
00000111
C A 7
C A 6
C
A 5
C A 4
C
A 3
C
A 2
C A
1
C A 0
Figure 19. Writing Character Address Byte in 8-Bit and 16-Bit Operation Modes
CS
SCLK
SDIN
MSB
12345678 12345678
9
10
11 121314 15 16
C A 7
C A 6
C A 5
C A 4
C A 3
C A
2
C
A 1
C A 0
X
1011XXXX
SDOUT
LSB
MSB
L B C
B L K
I N V
00000
LSB
Figure 20. Reading Character Address and Character Attribute Bytes in 16-Bit Operation Mode
CS
SCLK
SDIN
MSB LSB
12345678
D7
D6
D5
D4
D3
D2
D1 D0
Figure 21. Write Operation in Auto-Increment Mode
Software Reset
The MAX7456 features a Software Reset bit (VM0[1]) that, when set high, clears the display memory and resets all registers to their default values except the OSD Black Level register (OSDBL). After 100µs (typi­cal), STAT[6] can be polled to verify that the reset process is complete.
Hardware Reset
The MAX7456 provides a hardware reset input (RESET) that functions the same as the POR. All registers are
reset to their default values and are not accessible for reading/writing when RESET is driven low. The resetting process requires a 50ms wide RESET pulse, and no other activities are allowed during this interval. All SPI registers are reset to their default values 100µs after the rising edge of RESET. The display memory is reset to its default value of 00H in all locations 20µs after the ris­ing edge of RESET. RESET takes precedence over the Software Reset bit. After RESET has been deasserted, STAT[6] can be polled to verify that the reset sequence is complete.
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 23
SUPPLY
VOLTAGE
XTAL
OSCILLATOR
50ms
4.75V
0V
SPI
REGISTER
RESET
100µs
50ms
DISPLAY
MEMORY
CLEAR
20µs
POWER
ON
POWER STABLE
CLOCK STABLE
POWER-ON
RESET START
POR DEFAULT
STAT E
Figure 22. Power-On Reset Sequence
MAX7456
MAX7456 Register Description
Access to all MAX7456 operations, including display­memory and character-memory access, are through the SPI registers listed in Table 3. There is no direct access to the display and character memories through the SPI port. See the Applications Information section
for step-by-step descriptions of the SPI operations needed to access the memories.
The register format used in this data sheet is REGISTER_NAME [BIT_NUMBERS]. For example, bit 1 in Video Mode 0 register is written as VM0[1].
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
24 ______________________________________________________________________________________
Table 3. Register Map
WRITE
ADDRESS
READ
ADDRESS
REGISTER
NAME
REGISTER
DESCRIPTION
00H 80H VM0 Video Mode 0
01H 81H VM1 Video Mode 1
02H 82H HOS Horizontal Offset
03H 83H VOS Vertical Offset
04H 84H DMM Display Memory Mode
05H 85H DMAH Display Memory Address High
06H 86H DMAL Display Memory Address Low
07H 87H DMDI Display Memory Data In
08H 88H CMM Character Memory Mode
09H 89H CMAH Character Memory Address High
0AH 8AH CMAL Character Memory Address Low
0BH 8BH CMDI Character Memory Data In
0CH 8CH OSDM OSD Insertion Mux
10H 90H RB0 Row 0 Brightness
11H 91H RB1 Row 1 Brightness
12H 92H RB2 Row 2 Brightness
13H 93H RB3 Row 3 Brightness
14H 94H RB4 Row 4 Brightness
15H 95H RB5 Row 5 Brightness
16H 96H RB6 Row 6 Brightness
17H 97H RB7 Row 7 Brightness
18H 98H RB8 Row 8 Brightness
19H 99H RB9 Row 9 Brightness
1AH 9AH RB10 Row 10 Brightness
1BH 9BH RB11 Row 11 Brightness
1CH 9CH RB12 Row 12 Brightness
1DH 9DH RB13 Row 13 Brightness
1EH 9EH RB14 Row 14 Brightness
1FH 9FH RB15 Row 15 Brightness
6CH ECH OSDBL OSD Black Level
AxH STAT Status
BxH DMDO Display Memory Data Out
CxH CMDO Character Memory Data Out
X = Don’t care.
Video Mode 0 Register (VM0)
Write address = 00H, read address = 80H.
Read/write access: unrestricted.
To write to this register, the following conditions must be met:
1) STAT[5] = 0, the character memory (NVM) is not busy.
2) DMM[2] = 0, the display memory (SRAM) is not in the process of being cleared.
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 25
BIT DEFAULT FUNCTION
7 0 Don’t Care
60
Video Standard Select 0 = NTSC 1 = PAL
5, 4 00
Sync Select Mode (Table 1) 0x = Autosync select (external sync when LOS = 0 and internal sync when LOS = 1) 10 = External 11 = Internal
30
Enable Display of OSD Image 0 = Off 1 = On
20
Vertical Synchronization of On-Screen Data 0 = Enable on-screen display immediately 1 = Enable on-screen display at the next VSYNC
10
Software Reset Bit When this bit is set, all registers are set to their default values and the display memory is cleared. When a stable 27MHz clock is present, this bit is automatically cleared internally after typically 100µs. The user does not need to write a 0 afterwards. SPI operations should not be performed during this time or unpredictable results may occur. The status of the bit can be checked by reading this register after typically 100µs. This register is not accessible for writing until the display memory clear operation is finished (typically 20µs).
00
Video Buffer Enable 0 = Enable 1 = Disable (VOUT is high impedance)
X = Don’t care.
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
26 ______________________________________________________________________________________
Video Mode 1 Register (VM1)
Write address = 01H, read address = 81H.
Read/write access: unrestricted.
BIT DEFAULT FUNCTION
70
Background Mode (See Table 4) 0 = The Local Background Control bit (see DMM[5] and DMDI[7]) sets the state of each character background. 1 = Sets all displayed background pixels to gray. The gray level is specified by bits VM1[6:4] below. This bit overrides the local background control bit. Note: In internal sync mode, the background mode bit is set to 1.
6, 5, 4 100
Background Mode Brightness (% of OSD White Level) 000 = 0% 001 = 7% 010 = 14% 011 = 21% 100 = 28% 101 = 35% 110 = 42% 111 = 49%
3, 2 01
Blinking Time (BT) 00 = 2 fields (33ms in NTSC mode, 40ms in PAL mode) 01 = 4 fields (67ms in NTSC mode, 80ms in PAL mode) 10 = 6 fields (100ms in NTSC mode, 120ms in PAL mode) 11 = 8 fields (133ms in NTSC mode, 160ms in PAL mode)
1, 0 11
Blinking Duty Cycle (On : Off) 00 = BT : BT 01 = BT : (2 x BT) 10 = BT : (3 x BT) 11 = (3 x BT) : BT
Horizontal Offset Register (HOS)
Write address = 02H, read address = 82H.
Read/write access: unrestricted (Figure 23).
BIT DEFAULT FUNCTION
7, 6 00 Don’t Care
5–0 10 0000
Horizontal Position Offset (OSD video is not inserted into the horizontal blanking interval) 00 0000 = Farthest left (-32 pixels)
10 0000 = No horizontal offset
11 1111 = Farthest right (+31 pixels)
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 27
Vertical Offset Register (VOS)
Write address = 03H, read address = 83H.
Read/write access: unrestricted (Figure 23).
BIT DEFAULT FUNCTION
7, 6, 5 000 Don’t Care
4–0 1 0000
Vertical Position Offset (OSD video can be vertically shifted into the vertical blanking lines) 0 0000 = Farthest up (+16 pixels)
1 0000 = No vertical offset
1 1111 = Farthest down (-15 pixels)
Figure 23. Character Display Area
ROW NO.
0
VERTICAL POSITION OFFSET
HSYNC
DISPLAY AREA: NTSC: 13 ROWS x 30 COLUMNS PAL: 16 ROWS x 30 COLUMNS
HORIZONTAL POSITION OFFSET
15
VSYNC
360 PIXELS
NTSC: 234 LINES PAL: 288 LINES
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
28 ______________________________________________________________________________________
Display Memory Mode Register (DMM)
Write address = 04H, read address = 84H.
Read/write access: unrestricted.
To write to this register, the following condition must be met:
DMM[2] = 0, the display memory is not in the process of being cleared.
BIT DEFAULT FUNCTION
7 0 Don’t Care
60
Operation Mode Selection
0 = 16-bit operation mode The 16-bit operation mode increases the speed at which the display memory can be updated. When writing to the display memory, the attribute byte is not entered through the SPI-compatible interface. It is entered automatically by copying DMM[5:3] to a character’s attribute byte when a new character is written, thus reducing the number of SPI write operations per character from two to one (Figure 19). When in this mode, all characters written to the display memory have the same attribute byte. This mode is useful because successive characters commonly have the same attribute. This mode is distinct from the 8-bit operation mode where a character attribute byte must be written each time a character address byte is written to the display memory (see Table 5). When reading data from the display memory, both the Character Address byte and Character Attribute byte are transferred with the SPI-compatible interface (Figure 18).
1 = 8-bit operation mode The 8-bit operation mode provides maximum flexibility when writing characters to the display memory. This mode enables writing individual Character Attribute bytes for each character (see Table 5). When writing to the display memory, DMAH[1] = 0 directs the data to the Character Address byte and DMAH[1] = 1 directs the Character Attributes byte to the data. This mode is distinct from the 16-bit operation mode where the attribute bits are automatically copied from DMM[5:3] when a character is written.
50
Local Background Control Bit, LBC (see Table 4) Applies to characters written in 16-bit operating mode. 0 = Sets the background pixels of the character to the video input (VIN) when in external sync mode. 1 = Sets the background pixels of the character to the background mode brightness level defined by VM1[6:4] in external or internal sync mode. Note: In internal sync mode, the local background control bit behaves as if it is set to 1.
40
Blink Bit, BLK Applies to characters written in 16-bit operating mode. 0 = Blinking off 1 = Blinking on Note: Blinking rate and blinking duty cycle data in the Video Mode 1 (VM1) register are used for blinking control. In external sync mode: when the character is not displayed, VIN is displayed. In internal sync mode: when the character is not displayed, background mode brightness is displayed (see VM1[6:4]).
30
Invert Bit, INV Applies to characters written in 16-bit operating mode (see Figure 24). 0 = Normal (white pixels display white, black pixels display black) 1 = Invert (white pixels display black, black pixels display white)
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 29
Display Memory Mode Register (DMM) (continued)
BIT DEFAULT FUNCTION
20
Clear Display Memory 0 = Inactive 1 = Clear (fill all display memories with zeros) Note: This bit is automatically cleared after the operation is completed (the operation requires 20µs). The user does not need to write a 0 afterwards. The status of the bit can be checked by reading this register. This operation is automatically performed:
a) On power-up b) Immediately following the rising edge of RESET c) Immediately following the rising edge of CS after VM0[1] has been set to 1
10
Vertical Sync Clear Valid only when clear display memory = 1, (DMM[2] = 1) 0 = Immediately applies the clear display-memory command, DMM[2] = 1 1 = Applies the clear display-memory command, DMM[2] = 1, at the next VSYNC time
00
Auto-Increment Mode Auto-increment mode increases the speed at which the display memory can be written by automatically incrementing the character address for each successive character written. This mode reduces the number of SPI commands, and thus the time needed to write a string of adjacent characters. This mode is useful when writing strings of characters written from left-to-right, top-to­bottom, on the display (see Table 5).
0 = Disabled 1 = Enabled When this bit is enabled for the first time, data in the Display Memory Address (DMAH[0] and DMAL[7:0]) registers are used as the starting location to which the data is written. When performing the auto-increment write for the display memory, the 8-bit address is internally generated, and therefore only 8-bit data is required by the SPI-compatible interface (Figure 21). The content is to be interpreted as a Character Address byte if DMAH[1] = 0 or a Character Attribute byte if DMAH[1] = 1. This mode is disabled by writing the escape character 1111 1111. If the Clear Display Memory bit is set, this bit is reset internally.
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
30 ______________________________________________________________________________________
INVERT
BIT
DMM[3]
EXTERNAL SYNC MODE AND LOCAL
BACKGROUND CONTROL BIT (LBC) = 0
INTERNAL SYNC MODE OR LOCAL
BACKGROUND CONTROL BIT (LBC) = 1
0
1
Figure 24. Character Attribute Bit Examples: Invert and Local Background Control
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 31
Table 4. Character Background Control
SYNC MODE
BACKGROUND MODE,
VM1[7]
LOCAL BACKGROUND
CONTROL BIT, LBC
DMM[5], DMDI[7]
CHARACTER
BACKGROUND PIXEL
0 0 Input Video
0 1 Gray
External
1 X Gray
Internal X X Gray
X = Don’t care.
Display Memory Address High Register
(DMAH)
Write address = 05H, read address = 85H.
Read/write access: unrestricted.
To write to this register, the following condition must be met:
DMM[2] = 0, the display memory is not in the process of being cleared.
BIT DEFAULT FUNCTION
7–2 0000 00 Don’t Care
10
Byte Selection Bit This bit is valid only when in the 8-bit operation mode (DMM[6] = 1). 0 = Character Address byte is written to or read (DMDI[7:0] contains the Character Address byte). 1 = Character Attribute byte is written to or read (DMDI[7:0] contains the Character Attribute byte).
00
Display Memory Address Bit 8 This bit is the MSB of the display-memory address. The display-memory address sets the location of a character on the display (Figure 10). The lower order 8 bits of the display-memory address is found in DMAL[7:0].
Display Memory Address Low Register
(DMAL)
Write address = 06H, read address = 86H.
Read/write access: unrestricted.
To write to this register, the following condition must be met:
DMM[2] = 0, the display memory is not in the process of being cleared.
BIT DEFAULT FUNCTION
7–0 0000 0000
Display Memory Address Bits 7–0 This byte is the lower 8 bits of the display-memory address. The display-memory address sets the location of a character on the display (Figure 10). The MSB of the display-memory address is DMAH[0].
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
32 ______________________________________________________________________________________
Display Memory Data In Register (DMDI)
Write address = 07H, read address = 87H.
Read/write access: unrestricted.
To write to this register, the following condition must be met:
DMM[2] = 0, the display memory is not in the process of being cleared.
BIT DEFAULT FUNCTION
7–0 0000 0000
Character Address or Character Attribute byte to be stored in the display memory.
8-Bit Operation Mode (DMM[6] = 1) If DMAH[1] = 0, the content is to be interpreted as a Character Address byte, where
Bits 7–0 = Character Address bits, CA[7:0] (Figure 12).
If DMAH[1] = 1, the content is to be interpreted as a Character Attribute byte where
Bit 7 = Local Background Control bit, LBC (Figure 24 and Table 4) Bit 6 = Blink bit, BLK Bit 5 = Invert bit, INV (see Figure 24) Bit 4–0 = 0 (The LBC, BLK, and INV bits are described in the Display Memory Mode register.)
16-Bit Operation Mode (DMM[6] = 0) The content is always interpreted as a Character Address byte where bits 7–0 = CA[7:0] (Figure 12).
Auto-Increment Mode (DMM[0] = 1) The character address CA[7:0] = FFH is reserved for use as an escape character that terminates the auto-increment mode. Therefore, the character located at address FFH is not available for writing to the display memory when in auto-increment mode. In all other modes, character FFH is available.
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 33
Character Memory Mode Register (CMM)
Write address = 08H, read address = 88H.
Read/write access: unrestricted.
To write to this register, the following conditions must be met:
1) STAT[5] = 0, the character memory (NVM) is not busy.
2) VM0[3] = 0, the OSD is disabled.
X = Don’t care.
BIT DEFAULT FUNCTION
7–0 0000 0000
Only whole characters (54 bytes) can be written to or read from the nonvolatile character memory (NVM) at one time. This is done through the (64 byte) shadow RAM (Figure 13). The shadow RAM is accessed through the SPI port one byte at a time. The shadow RAM is written to and read from NVM by the following procedures:
Writing to NVM
1010 XXXX = Write to NVM array from shadow RAM. The 64 bytes from shadow RAM are written to the NVM array at the character-memory address location (CMAH, CMAL) (Figure 13). The character memory is busy for approximately 12ms during this operation. During this time, STAT[5] is automatically set to 1. The Character Memory Mode register is cleared and STAT[5] is reset to 0 after the write operation has been completed. The user does not need to write zeros afterwards.
Reading from NVM
0101 XXXX = Read from NVM array into shadow RAM. The 64 bytes corresponding to the character-memory address (CMAH, CMAL) are read from the NVM array into the shadow RAM (Figure 13). The character memory is busy for approximately 0.5µs during this operation. The CMM register is cleared after the operation is completed. The user does not need to write zeros afterwards. During this time, STAT[5] is automatically set to 1. STAT[5] is reset to 0 when the read operation has been complete.
If the display has been enabled (VM0[3] = 1) or the character memory is busy (STAT[5] = 1), NVM read/write operation commands are ignored and the corresponding registers are not updated. However, all the registers can be read at any time.
For all the character-memory operations, the character address is formed with Character Memory Address High (CMAH[7:0]) and Character Memory Address Low (CMAL[7:0]) register bits (Figures 11, 12, and 13).
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
34 ______________________________________________________________________________________
Character Memory Address High Register
(CMAH)
Write address = 09H, read address = 89H.
Read/write access: unrestricted.
To write to this register, the following conditions must be met:
1) STAT[5] = 0, the character memory (NVM) is not busy.
2) VM0[3] = 0, the OSD is disabled.
BIT DEFAULT FUNCTION
7–0 0000 0000
Character Memory Address Bits These 8 bits point to a character in the character memory (256 characters total in NVM) (Figures 10 and 12).
Character Memory Address Low Register
(CMAL)
Write address = 0AH, read address = 8AH.
Read/write access: unrestricted.
To write to this register, the following conditions must be met:
1) STAT[5] = 0, the character memory (NVM) is not busy.
2) VM0[3] = 0, the OSD is disabled.
BIT DEFAULT FUNCTION
7, 6 00 Don’t Care
5–0 00 0000
Character Memory Address Bits These 6 bits point to one of the 64 bytes (only 54 used) that represent a 4-pixel group in the character (Figures 10 and 11).
Character Memory Data In Register (CMDI)
Write address = 0BH, read address = 8BH.
Read/write access: unrestricted.
To write to this register, the following conditions must be met:
1) STAT[5] = 0, the character memory (NVM) is not busy.
2) VM0[3] = 0, the OSD is disabled.
BIT DEFAULT FUNCTION
7, 6 NA Leftmost pixel. 00 = Black, 10 = White, 01 or 11 = Transparent (see Figure 11)
5, 4 NA Left center pixel. 00 = Black, 10 = White, 01 or 11 = Transparent (see Figure 11)
3, 2 NA Right center pixel. 00 = Black, 10 = White, 01 or 11 = Transparent (see Figure 11)
1, 0 NA Rightmost pixel. 00 = Black, 10 = White, 01 or 11 = Transparent (see Figure 11)
NA = Not applicable.
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 35
OSD Insertion Mux Register (OSDM)
Write address = 0CH, read address = 8CH.
Read/write access: unrestricted.
BIT DEFAULT FUNCTION
7, 6 00 Don’t Care
5, 4, 3 011
OSD Rise and Fall Time—typical transition times between adjacent OSD pixels 000: 20ns (maximum sharpness/maximum crosscolor artifacts ) 001: 30ns 010: 35ns 011: 60ns 100: 80ns 101: 110ns (minimum sharpness/minimum crosscolor artifacts)
2, 1, 0 011
OSD Insertion Mux Switching Time–typical transition times between input video and OSD pixels 000: 30ns (maximum sharpness/maximum crosscolor artifacts ) 001: 35ns 010: 50ns 011: 75ns 100: 100ns 101: 120ns (minimum sharpness/minimum crosscolor artifacts)
Row N Brightness Register
(RB0–RB15)
Address = 10H + row number; write address = 10H through 1FH, read address = 90H through 9FH, read/write access: unrestricted.
Top row number is 0. Bottom row number is 13 in NTSC mode and 15 in PAL mode (see Figure 23).
BIT DEFAULT FUNCTION
7–4 0000 Don’t Care
3, 2 00
Character Black Level —All the characters in row N use these brightness levels for the black pixel, in % of OSD white level. 00 = 0% 01 = 10% 10 = 20% 11 = 30%
1, 0 01
Character White Level —All the characters in row N use these brightness levels for the white pixel, in % of OSD white level. 00 = 120% 01 = 100% 10 = 90% 11 = 80%
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
36 ______________________________________________________________________________________
OSD Black Level Register (OSDBL)
Write address = 6CH, read address = ECH.
Read/write access: This register contains 4 factory-pre­set bits [3:0] that must not be changed. Therefore,
when changing bit 4, first read this register, modify bit 4, and then write back the updated byte.
BIT DEFAULT FUNCTION
7–5 000 Don’t Care
41
OSD Image Black Level Control This bit enables the alignment of the OSD image black level with the input image black level at
VOUT. Always enable this bit following power-on reset to ensure the correct OSD image brightness.
0 = Enable automatic OSD black level control 1 = Disable automatic OSD black level control
0–3 xxxx
These bits are factory preset. To ensure proper operation of the MAX7456, do not change the values of these bits.
xxxx = Factory preset—can be any one of the 16 possible values. This value is permanently stored in the MAX7456 and will always be restored to the factory preset value following power-on reset or hardware reset.
Status Register (STAT)
Read address = AxH.
Read/write access: read only.
BIT DEFAULT FUNCTION
7 NA Don’t Care
6NA
Reset M od e 0 = C l ear w hen p ow er - up r eset m od e i s com p l ete. O ccur s 50m s ( typ ) fol l ow i ng stab l e V
D D
( Fi g ur e 22)
1 = S et w hen i n p ow er - up r eset m od e
5NA
Character Memory Status 0 = Available to be written to or read from 1 = Unavailable to be written to or read from
4NA
VSYNC Output Level 0 = Active during vertical sync time 1 = Inactive otherwise
3NA
HSYNC Output Level 0 = Active during horizontal sync time 1 = Inactive otherwise
2NA
Loss-of-Sync (LOS) 0 = Sync Active. Asserted after 32 consecutive input video lines. 1 = No Sync. Asserted after 32 consecutive missing input video lines.
1NA
0 = NTSC signal is not detected at VIN 1 = NTSC signal is detected at VIN
0NA
0 = PAL signal is not detected at VIN 1 = PAL signal is detected at VIN
NA = Not applicable. X = Don’t care.
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 37
Display Memory Data Out Register (DMDO)
Read address = BxH.
Read/write access: read only.
To write to this register the following condition must be met:
DMM[2] = 0, the display memory is not in the process of being cleared.
BIT DEFAULT FUNCTION
7–0 NA
Character Address or Character Attribute byte to be read from the display memory.
8-Bit Operation Mode (DMM[6] = 1): If DMAH[1] = 0, the content is to be interpreted as a Character Address byte, where
Bits 7–0 = Character Address bits, CA[7:0] (Figure 12)
If DMAH[1] = 1, the content is to be interpreted as a Character Attribute byte where
Bit 7 = Local Background Control bit, LBC (see Figure 24 and Table 4) Bit 6 = Blink bit, BLK Bit 5 = Invert bit, INV (see Figure 24) Bit 4–0 = 0 The LBC, BLK, and INV bits are described in the Display Memory Mode register.
16-Bit Operation Mode (DMM[6] = 0): The content is to be interpreted as a Character Address byte, where
Bits 7–0 = CA[7:0] (see Figure 12)
followed by a Character Attribute byte, where
Bit 7 = 0 Bit 6 = Local Background Control bit, LBC (see Figure 24 and Table 4) Bit 5 = Blink bit, BLK Bit 4 = Invert bit, INV (see Figure 24) Bit 3–0 = 0 The LBC, BLK, and INV bits are described in the Display Memory Mode register.
NA = Not applicable. X = Don’t care.
Character Memory Data Out Register
(CMDO)
Read address = CxH.
Read/write access: read only.
To write to this register, the following conditions must be met:
1) STAT[5] = 0, the character memory (NVM) is not busy.
2) VM0[3] = 0, the OSD is disabled.
BIT DEFAULT FUNCTION
7, 6 NA Leftmost pixel. 00 = Black, 10 = White, 01 or 11 = Transparent (see Figure 11)
5, 4 NA Left center pixel. 00 = Black, 10 = White, 01 or 11 = Transparent (see Figure 11)
3, 2 NA Right center pixel. 00 = Black, 10 = White, 01 or 11 = Transparent (see Figure 11)
1, 0 NA Rightmost pixel. 00 = Black, 10 = White, 01 or 11 = Transparent (see Figure 11)
NA = Not applicable. X = Don’t care.
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
38 ______________________________________________________________________________________
Applications Information
Character-Memory Operation
Only whole characters (54 bytes of pixel data) can be written to or read from the NVM character memory at one time. This is done through the (64 byte) shadow RAM (see Figure 13). The shadow RAM is accessed by the SPI port one byte at a time. The shadow RAM is written to and read from the NVM by a single SPI command.
Steps for Writing Character Bytes
into the NVM Character Memory
Writing a new character:
1) Write VM0[3] = 0 to disable the OSD image display.
2) Write CMAH[7:0] = xxH to select the character (0–255) to be written (Figures 10 and 13).
3) Write CMAL[7:0] = xxH to select the 4-pixel byte (0–63) in the character to be written (Figures 10 and
13).
4) Write CMDI[7:0] = xxH to set the pixel values of the selected part of the character (Figures 11 and 13).
5) Repeat steps 3 and 4 until all 54 bytes of the char­acter data are loaded into the shadow RAM.
6) Write CMM[7:0] = 1010xxxx to write to the NVM array from the shadow RAM (Figure 13). The char­acter memory is busy for approximately 12ms dur­ing this operation. STAT[5] can be read to verify that the NVM writing process is complete.
7) Write VM0[3] = 1 to enable the OSD image display.
Modifying an existing character:
1) Write VM0[3] = 0 to disable the OSD image display.
2) Write CMAH[7:0] = xxH to select the character (0–255) to be modified (Figures 10 and 13).
3) Write CMM[7:0] = 0101xxxx to read character data from the NVM to the shadow RAM (Figure 13).
4) Write CMAL[7:0] = xxH to select the 4-pixel byte (0–63) in the character to be modified (Figures 10 and 13).
5) Read CMDO[7:0] = xxH to read the byte of 4-pixel data to be modified (Figures 11 and 13).
6) Modify the byte of 4-pixel data as desired.
7) Write CMDI[7:0] = xxH to write the modified byte of 4-pixel data back to the shadow RAM (Figures 11 and 13).
8) Repeat steps 4 through 7 as needed until all pixels have been loaded into the shadow RAM.
9) Write CMM[7:0] = 1010xxxx to write the shadow RAM data to the NVM (Figure 13). The character
memory is busy for typically 12ms during this oper­ation. STAT[5] can be read to verify that the NVM writing process is complete.
10) Write VM0[3] =1 to enable the OSD image display.
Steps for Reading Character
Bytes from Character Memory
1) Write VM0[3] = 0 to disable the OSD image.
2) Write CMAH[7:0] = xxH to select the character (0–255) to be read (Figures 10 and 13).
3) Write CMM[7:0] = 0101xxxx to read the character data from the NVM to the shadow RAM (Figure 13).
4) Write CMAL[7:0] = xxH to select the 4-pixel byte (0–63) in the character to be read (Figures 10 and 13).
5) Read CMDO[7:0] = xxH to read the selected 4-pixel byte of data (Figures 11 and 13).
6) Repeat steps 4 and 5 to read other bytes of 4-pixel data.
7) Write VM0[3] = 1 to enable the OSD image display.
Display-Memory Operation
The following two steps enable viewing of the OSD image. These steps are not required to read from or write to the display memory:
1) Write VM0[3] = 1 to enable the display of the OSD image.
2) Write OSDBL[4] = 0 to enable automatic OSD black level control. This ensures the correct OSD image brightness. This register contains 4 factory-preset bits [3:0] that must not be changed. Therefore, when changing bit 4, first read OSDBL[7:0], modify bit 4, and then write back the updated byte.
Steps for Clearing Display Memory
Write DMM[2] = 1 to start the clear display-memory operation. This operation typically takes 20µs. The Display Memory Mode register cannot be written to again until the clear operation is complete. DMM[2] is automatically reset to zero upon completion.
Steps for Writing to
Display Memory in 8-Bit Mode
The 8-bit operation mode provides maximum flexibility when writing characters to the display memory. This mode enables writing individual Character Attribute bytes for each character (see Table 5). This mode is distinct from the 16-bit operation mode where the Character Attribute byte is automatically copied from DMM[5:3] when a character is written (Figure 19).
Write DMM[6] = 1 to select the 8-bit operation mode.
Writing the Character Address Byte to the Display Memory:
1) Write DMAH[1] = 0 to write a Character Address byte.
2) Write DMAH[0] = x to select the MSB and DMAL[7:0] = xxH to select the lower order bits of the address where the character data is to be writ­ten. This address determines the location of the character on the display (see Figure 10).
3) Write the Character Address byte (CA[7:0]) to be written to the display memory to DMDI[7:0] (see Figures 10, 12, and 19).
Writing the Character Attribute Byte to the Display Memory:
1) Write DMAH[1] = 1 to write a Character Attribute byte.
2) Write DMAH[0] = x to select the MSB and DMAL[7:0] = xxH to select the lower order bits of the address where the character data is to be writ­ten. This address determines the location of the character on the display (Figure 10).
3) Write the Character Attribute byte to be written to the display memory to DMDI[7:0] (see Figures 10 and 19).
Steps for Writing to
Display Memory in 16-Bit Mode
The 16-bit operation mode increases the speed at which the display memory can be updated. This is done by automatically copying DMM[5:3] to a Character’s Attribute byte when a new character is writ­ten, thus reducing the number of SPI write operations per character from two to one (Figure 19). When in this mode, all characters written to the display memory have the same attribute byte. This mode is useful because successive characters commonly have the same attribute. This mode is distinct from the 8-bit operation mode where a Character Attribute byte must be written each time a Character Address byte is writ­ten to the display memory (see Table 5).
1) Write DMM[6] = 0 to select the 16-bit operation mode.
2) Write DMM[5:3] = xxx to set the Local Background Control (LBC), Blink (BLK), and Invert (INV) attribute bits that will be applied to all characters written to the display memory while in the 16-bit operation mode.
3) Write DMAH[0] = x to select the MSB and DMAL[7:0] = xxH to select the lower order bits of the address where the character data is to be written.
This address determines the location of the charac­ter on the display (see Figure 10).
4) Write the Character Address byte (CA[7:0]) to be written to the display memory into DMDI[7:0]. It will be stored along with a Character Attribute byte derived from DMM[5:3] (Figures 12 and 19).
Steps for Writing to Display Memory
in Auto-Increment Mode
Auto-increment mode increases the speed at which the display memory can be written by automatically incre­menting the character address for each successive character written. This mode is useful when writing strings of characters written from left-to-right and top­to-bottom on the display. This mode reduces the num­ber of SPI commands (see Table 5).
When in 8-Bit Operating Mode:
1) Write DMM[0] = 1 to set the auto-increment mode.
2) Write to DMM[6] = 1 to set the 8-bit operation mode.
3) Write DMAH[1] = 0 to select if a Character Address byte will be written or DMAH[1] = 1 to select if a Character Attribute byte will be written.
4) Write DMAH[0] = x to select the MSB and DMAL[7:0] to select the lower order address bits, of the starting address for auto-increment operation. This address determines the location of the charac­ter on the display (see Figures 10 and 21).
5) Write to DMDI[7:0] to store character data (Character Address or Character Attribute bytes) to the current display-memory address. The display-memory address is automatically incremented following the write operation. Subsequent characters are succes­sively written from left-to-right and top-to-bottom on the display (see Figure 10). Repeat until the final display­memory address is reached.
6) Write DMDI[7:0] = FFH to terminate the auto-incre­ment mode. Note that the character stored at CA[7:0] = FFH is not available for use when in auto­increment mode.
When in 16-Bit Operating Mode:
1) Write DMM[0] = 1 to set the auto-increment mode.
2) Write DMM[6] = 0 to set the 16-bit operation mode.
3) Write DMM[5:3] = xxx to set the Local Background Control (LBC), Blink (BLK), and Invert (INV) attribute bits that will be applied to all characters.
4) Write DMAH[0] = x to select the MSB and DMAL[7:0] to select the lower order address bits, of the starting address for auto-increment operation.
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 39
MAX7456
This address determines the location of the charac­ter on the display (see Figures 10 and 21).
5) Write the Character Address byte (CA[7:0]) to be written to the display memory into DMDI[7:0]. It will be stored along with a Character Attribute byte derived from DMM[5:3] (see Figure 19). The dis­play-memory address is automatically incremented following the write operation. Repeat until the final display-memory address is reached.
6) Write DMDI[7:0] = FFH to terminate the auto-incre­ment mode. Note that the character stored at CA[7:0] = FFH is not available for use when in auto­increment mode.
Steps for Reading from Display
Memory in 8-Bit Mode
1) Write DMM[6] = 1 to select the 8-bit operation mode.
2) Write DMAH[1] = 0 to read the Character Address byte or DMAH[1] = 1 to read the Character Attribute byte.
3) Write to DMAH[0] to select the MSB of the address where data must be read from (Figure 10).
4) Write to DMAL[7:0] to select all the lower order bits, except for the MSB, of the address where data must be read from (Figure 10).
5) Read DMDO[7:0] to read the data from the selected location in the display memory (Figure 10).
Steps for Reading from Display
Memory in 16-Bit Mode
1) Write DMM[6] = 0 to select the 16-bit operation mode.
2) Write DMAH[0] = x to select the MSB and DMAL[7:0] = xxH to select the lower order bits of the address where the character data is to be read. This address determines the location of the charac­ter on the display (see Figure 10).
3) Read DMDO[15:0] to read the Character Address byte and the Character Attribute byte from the selected location in the display memory. The first data byte is the Character Address (CA[7:0]), and the second byte contains the Character Attribute bits (Figure 20). Note that the bit positions of the Character Attribute byte when read, differ from when they are written. See the Display Memory Data Out Register (DMDO) section and Figure 20 for a description of the bit locations of the attribute bits when reading.
Note: If an internal display-memory read request occurs simultaneously with an SPI display-memory operation, the internal read request is ignored, and the display of that character, during that field time, may appear to momentarily break up. See the Synchronous OSD Updates section.
Synchronous OSD Updates
The display of a character may momentarily appear to break up if an internal display-memory read request occurs simultaneously with an SPI display-memory operation. Momentary breakup of the OSD image can be prevented by writing to the display memory during the vertical blanking interval. This can be achieved by using VSYNC as an interrupt to the host processor to initiate writing to the display memory. Alternatively, the OSD image can be synchronously disabled before writ­ing to the display memory and synchronously re­enabled afterwards (see VM0[3:2]).
Multiple OSDs with
Common Clock Application
The MAX7456 provides a TTL clock output (CLKOUT) capable of driving one CLKIN pin of another MAX7456. Two or more MAX7456 parts can be driven using an external clock driver. This arrangement reduces the system cost by having only one crystal on one MAX7456 that supplies the clock signal to multiple MAX7456 parts (Figure 25).
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
40 ______________________________________________________________________________________
Table 5. Display-Memory Access Modes and SPI Operations
OPERATING
MODE
AUTO-INCREMENT
DMM[0] = 0
No. OF READ
OPERATIONS
No. OF WRITE
OPERATIONS
AUTO-INCREMENT
DMM[0] = 1
No. OF WRITE OPERATIONS
One-time setup 2 1 One-time setup 6
16-Bit Mode DMM[6] = 0
Per character 3 3 Per character 1
One-time setup 1 1 One-time setup 6
8-Bit Mode
DMM[6] = 1
Per character 6 6 Per character 1
MODE DISABLED
MODE ENABLED
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
______________________________________________________________________________________ 41
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
MAX7456
SDIN
+5V
27MHz
SDOUT
+5V
CVBS OUT1
SAG
PGND
RESET
HSYNC
VSYNC
DGND
CLKIN
XFB
CLKOUT
CS
SDIN
SCLK
SDOUT
LOS
N.C.
SCLK
CS1
CVBS IN1
LOS1
VS1
HS1
N.C.
N.C.
N.C.
N.C.
N.C.
AGND
N.C.
N.C.
+5V
0.1µF
C
OUT
75
75
1k1k1k
0.1µF
+5V
1k1k1k
0.1µF
0.1µF
C
SAG
C
OUT
C
SAG
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
MAX7456
+5V
CLOCK DRIVER
+5V
CVBS OUT2
SAG
PGND
RESET
HSYNC
VSYNC
DVDD
DGND
CLKIN
XFB
CLKOUT
CS
SDIN
SCLK
SDOUT
LOS
N.C.
CS2
CVBS IN2
LOS2
VS2
HS2
N.C.
N.C.
N.C.
N.C.
N.C.
AGND
N.C.
N.C.
0.1µF
TO OTHER
MAX7456 PARTS
AS NEEDED
VOUT
PVDD
VIN
AVDD
75
75
0.1µF
0.1µF
0.1µF
DVDD
VOUT
PVDD
VIN
AVDD
+
+
Figure 25. Typical Multiple OSDs with Daisy-Chained Clock
MAX7456
Single-Channel Monochrome On-Screen Display with Integrated EEPROM
42 ______________________________________________________________________________________
Selecting a Clock Crystal
Choose a 27MHz parallel resonant, fundamental mode crystal. No external load capacitors are needed. All capacitors required for the Pierce oscillator are includ­ed on-chip.
Power Supply and Bypassing
The MAX7456 operates from three independent supply lines. Each supply must be within a +4.75V to +5.25V voltage range. Separate the digital power supply from the analog and video-driver supply lines to prevent high-frequency digital noise that may couple onto the video output. All three supplies should be at the same DC voltage. Bypass each supply with a 0.1µF capacitor to ground very close to the IC pins. There are no power-supply sequencing requirements for the device.
Layout Concerns
For best performance, make the VIN and VOUT traces as short as possible. Place all AC-coupling capacitors and 75termination resistors close to the device with the resistors terminated to the solid analog ground plane. Since the MAX7456 TSSOP package has an exposed pad (EP) underneath, do not run traces under the package to avoid possible short circuits. Refer to the MAX7456 EV kit for an example of PCB layout.
To aid heat dissipation, the EP should be connected to a similarly sized pad on the component side of the PCB. This pad should be connected through to the sol­der-side copper by several plated holes to conduct heat away from the device. The solder-side copper pad area should be larger than the EP area. It is recom­mended that the EP be connected to ground, but it is not required. Do not use EP as the only ground connec­tion for the device.
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
N.C.
N.C.
VOUT
SAG
PVDD
PGND
N.C.
VIN
AVDD
AGND
RESET
HSYNC
VSYNC
N.C.
N.C.
N.C.
LOS
SDOUT
SCLK
SDIN
CS
CLKOUT
XFB
CLKIN
DGND
DVDD
N.C.
N.C.
TSSOP
TOP VIEW
MAX7456
+
Pin Configuration
Chip Information
PROCESS: BiCMOS
MAX7456
Single-Channel Monochrome On-Screen
Display with Integrated EEPROM
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 43
© 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages
.)
AA AA
TSSOP 4.4mm BODY.EPS
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