• Controlled rise/fall times of output syncs and blanking
• Down-mode of DACs
• CVBS and S-Video output simultaneously
• PLCC68 package.
GENERAL DESCRIPTION
The SAA7185 encodes digital YUV video data to an
NTSC, PAL CVBS or S-Video signal.
The circuit accepts CCIR compatible YUV data with
720 active pixels per line in 4:2:2 multiplexed formats,
for example MPEG decoded data. It includes a sync/clock
generator and on-chip Digital-to-Analog Converters
(DACs).
The circuit is compatible to the DIG-TV2 chip family.
QUICK REFERENCE DATA
SYMBOLPARAMETERMIN.TYP.MAX.UNIT
V
V
I
DDA
I
DDD
V
V
DDA
DDD
i
o(p-p)
analog supply voltage4.755.05.25V
digital supply voltage4.55.05.5V
analog supply current−5055mA
digital supply current−140170mA
input signal voltage levelsTTL compatible
analog output signal voltages Y, C and CVBS without load
−2−V
(peak-to-peak value)
R
L
load resistance80−−Ω
ILELF integral linearity error−−±2LSB
DLELF differential linearity error−−±1LSB
T
DP42
DP53
DP64
DP75
RCV16Raster Control 1 for Video port. Depending on the synchronization mode, this pin
RCV27Raster Control 2 for Video port. Depending on the synchronization mode, this pin
V
SSD2
VP09
VP110
VP211
VP312
VP413
VP514
VP615
VP716
V
DDD1
SEL_ED18Select Encoder Data. Selects data either from MPEG port or from video port as encoder input.
V
SSD3
MP720
MP621
MP522
MP423
MP324
MP225
MP126
MP027
V
SSD4
RCM129Raster Control 1 for MPEG port. This pin provides a VS/FS/FSEQ signal.
RCM230Raster Control 2 for MPEG port. This pin provides an HS pulse for the MPEG decoder.
KEY31Key signal for OSD. It is active HIGH.
OSD032
OSD234
V
SSD5
CDIR36Clock direction. If the CDIR input is HIGH, the circuit receives a clock signal, otherwise LLC
V
DDD2
1digital ground 1
Upper 4 bits of the Data Port. If pin 68 (SEL_MPU) is HIGH, this is the data bus of the parallel
MPU interface. If it is LOW, they are the UV lines of the Video Port.
receives/provides a VS/FS/FSEQ signal.
receives/provides an HS/HREF/CBL signal.
8digital ground 2
Video Port. This is an input for CCIR 656 compatible, multiplexed video data. If the 16-bit
DIG-TV2 format is used, this is the Y data.
17digital supply voltage 1
19digital ground 3
MPEG Port. It is an input for CCIR 656 style multiplexed YUV data.
28digital ground 4
On-Screen Display data. This is the index for the internal OSD look-up table.OSD133
35digital ground 5
and CREF are generated by the internal crystal oscillator.
37digital supply voltage 2
1996 Jul 084
Philips SemiconductorsPreliminary specification
Digital Video Encoder (DENC2)SAA7185
SYMBOLPINDESCRIPTION
LLC38Line-Locked Clock. This is the 27 MHz master clock for the encoder. The direction is set by
the CDIR pin.
C
ref
XTALO40Crystal oscillator output (to crystal).
XTALI41Crystal oscillator input (from crystal). If the oscillator is not used, this pin should br connected
V
SSD6
RTCI43Real Time Control Input. If the clock is provided by an SAA7151B, RTCI should be connected
AP44Test pin. Connect to digital ground for normal operation.
SP45Test pin. Connect to digital ground for normal operation.
V
refL
V
refH
V
DDA1
CHROMA49Analog output of the chrominance signal.
V
DDA2
Y51Analog output of the luminance signal.
V
SSA
CVBS53Analog output of the CVBS signal.
V
DDA3
I
I
V
DDA4
RESET57Reset input, active LOW. After reset is applied, all outputs are in 3-state input mode.
DTACK58Data acknowledge output of the parallel MPU interface, active LOW, otherwise high
W/SCL59If pin 68 (SEL_MPU) is HIGH, this is the read/write signal of the parallel MPU interface,
R
A0/SDA60If pin 68 (SEL_MPU) is HIGH, this is the address signal of the parallel MPU interface,
CS/SA61If pin 68 (SEL_MPU) is HIGH, this is the chip select signal of the parallel MPU interface,
V
SSD7
DP063
DP164
DP265
DP366
V
DDD3
SEL_MPU68Select MPU interface input. If it is HIGH, the parallel MPU interface is active, otherwise the
39Clock Reference signal. This is the clock qualifier for DIG-TV2 compatible signals.
to ground.
42digital ground 6
to the RTCO pin of the decoder to improve the signal quality.
46Lower reference voltage input for the DACs.
47Upper reference voltage input for the DACs.
48Analog positive supply voltage 1 for the DACs and output amplifiers.
50Analog supply voltage 2 for the DACs and output amplifiers.
52Analog ground for the DACs and output amplifiers.
54Analog supply voltage 3 for the DACs and output amplifiers.
55Current input for the output amplifiers, connect via a 15 kΩ resistor to V
DDA
.
56Analog supply voltage 4 for the DACs and output amplifiers.
The I2C-bus receiver waits for the start condition.
impedance.
otherwise it is the I2C-bus serial clock input.
2
otherwise it is the I
C-bus serial data input/output.
otherwise it is the I2C-bus slave address select pin. LOW: slave address = 88H, HIGH = 8CH.
62digital ground 7
Lower 4 bits of the Data Port. If pin 68 (SEL_MPU) is HIGH, this is the data bus of the parallel
MPU interface. If it is LOW, they are the UV lines of the Video Port.
The digital MPEG-compatible Video Encoder (DENC2)
encodes digital luminance and chrominance into analog
CVBS and simultaneously S-Video (Y/C) signals. NTSC-M
and PAL B/G standards also sub-standards are supported.
The basic encoder function consists of subcarrier
generation and colour modulation also insertion of
synchronization signals. Luminance and chrominance
signals are filtered in accordance with the standard
requirements RS-170-A and CCIR 624.
For ease of analog post filtering the signals are twice
oversampled with respect to pixel clock before
digital-to-analog conversion.
For total filter transfer characteristics see Figs 3, 4,
5 and 6. The DACs are realized with full 10-bit resolution.
The encoder provides three 8-bit wide data ports, that
serve different applications.
The MPEG Port (MP) and the Video Port (VP) accept
8 lines multiplexed Cb-Y-Cr data.
The Video Port (VP) is also able to handle DIG-TV2 family
compatible 16-bit YUV signals. In this event, the Data Port
(DP) is used for the U/V components.
The Data Port can handle the data of an 8-bit wide
microprocessor interface, alternatively.
The 8-bit multiplexed Cb-Y-Cr formats are CCIR 656
(D1 format) compatible, but the SAV, EAV etc. codes are
not decoded.
A crystal-stable master clock (LLC) of 27 MHz, which is
twice the CCIR line-locked pixel clock of 13.5 MHz, needs
to be supplied externally. Optionally, a crystal oscillator
input/output pair of pins and an on-chip clock driver is
provided. Additionally, a DMSD2 compatible clock
interface, using C
sheet SAA7151B”
The DENC2 synthesizes all necessary internal signals,
colour subcarrier frequency, and synchronization signals,
from that clock. DENC2 is always timing master for the
MPEG Port (MP), but it can additionally be configured as
master or slave for the Video Port (VP).
The IC also contains Closed Caption and Extended Data
Services Encoding (Line 21); it also supports OSD via
KEY and three-bit overlay techniques by a 24 × 8 LUT.
The IC can be programmed via I2C-bus or 8-bit MPU
interface, but only one interface configuration can be
active at a time; if the 16-bit Video Port mode (VP and DP)
is being used, only the I2C-bus interface can be selected.
(input or output) and RTC (see
ref
) is available.
“data
A number of possibilities are provided for setting of
different video parameters such as:
black and blanking level control
colour subcarrier frequency
black variable burst amplitude etc.
During reset (
all digital I/O stages are set to input mode. A reset forces
the control interfaces to abort any running bus transfer and
to set Register 3AH to contents 13H, Register 61H to
contents 0X010101b, and Register 6CH to contents 00H.
All other control registers are not influenced by a reset.
Data manager
In the Data manager, real time arbitration on the data
stream to be encoded is performed.
Depending on hardware conditions (signals on pins
SEL_ED, KEY, OSD2 to OSD0, MP7 to to MP0,
VP7 to VP0 and DP7 to DP0) and different software
programming either data from the MP port, from the
VP port, or from the OSD port are selected to be encoded
to CVBS and Y/C signals.
Optionally, the OSD colour look-up tables located in this
block, can be read out in a pre-defined sequence (8 steps
per active video line), achieving e.g. a colour bar test
pattern generator without need for an external data
source. The colour bar function is only under software
control.
Encoder
IDEO PATH
V
The encoder generates out of Y, U and V baseband
signals luminance and colour subcarrier output signals,
suitable for use as CVBS or separate Y/C signals.
Luminance is modified in gain and in offset (latter
programmable in a certain range to enable different black
level set-ups). After having been inserted a fixed
synchronization level, in accordance with standard
composite synchronization schemes, a variable blanking
level, programmable also in a certain range, is inserted.
In order to enable easy analog post filtering, luminance is
interpolated from 13.5 MHz data rate to 27 MHz data rate,
providing luminance in 10-bit resolution. This filter is also
used to define smoothed transients for synchronization
pulses and blanking period. For transfer characteristic of
the luminance interpolation filter see Figs 5 and 6.
RESET = LOW) and after reset is released,
1996 Jul 087
Philips SemiconductorsPreliminary specification
Digital Video Encoder (DENC2)SAA7185
Chrominance is modified in gain (programmable
separately for U and V), standard dependent burst is
inserted, before baseband colour signals are interpolated
from 6.75 MHz data rate to 27 MHz data rate. One of the
interpolation stages can be bypassed, thus providing a
higher colour bandwidth, which can be made use of for Y/C
output. For transfer characteristics of the chrominance
interpolation filter see Figs 3 and 4.
The amplitude of inserted burst is programmable in a
certain range, suitable for standard signals and for special
effects. Behind the succeeding quadrature modulator,
colour in 10-bit resolution is provided on subcarrier.
The numeric ratio between Y and C outputs is in
accordance with set standards.
C
LOSED CAPTION ENCODER
Using this circuit, data in accordance with the specification
of Closed Caption or Extended Data Service, delivered by
the control interface, can be encoded (Line 21). Two
dedicated pairs of bytes (two bytes per field), each pair
preceded by run-in clocks and framing code, are possible.
The actual line number where data is to be encoded in, can
be modified in a certain range.
Data clock frequency is in accordance with definition for
NTSC-M standard 32 times horizontal line frequency.
Data LOW at the output of the DACs corresponds to 0 IRE,
data HIGH at the output of the DACs corresponds to
approximately 50 Ω.
It is also possible to encode Closed Caption Data for 50 Hz
field frequencies at 32 times horizontal line frequency.
Output Interface
In the output interface encoded Y and C signals are
converted from digital-to-analog in 10-bit resolution both Y
and C signals are combined to a 10-bit CVBS signal, also;
in front of the summation point, the luminance signal can
optionally be fed through a further filter stage, suppressing
components in the range of subcarrier frequency. Thus, a
type of Cross Colour reduction is provided, which is useful
in a standard TV set with CVBS input.
Slopes of synchronization pulses are not affected with any
Cross Colour reduction active.
Three different filter characteristics or bypass are
available, see Fig.5.
The CVBS output occurs with the same processing delay
as the Y and C outputs. Absolute amplitudes at the input
of the DAC for CVBS is reduced by
and C DACs to make maximum use of conversion ranges.
Outputs of all DACs can be set together via software
control to minimum output voltage for either purpose.
Synchronization
The synchronization of the DENC2 is able to operate in
two modes; slave mode and master mode.
In the slave mode, the circuit accepts synchronization
pulses at the bidirectional RCV1 port. The timing and
trigger behaviour related to the video signal on VP (and
DP, if used) can be influenced by programming the polarity
and on-chip delay of RCV1. Active slope of RCV1 defines
the vertical phase and optionally the odd/even and colour
frame phase to be initialized, it can be also used to set the
horizontal phase.
If the horizontal phase is not be influenced by RCV1, a
horizontal pulse needs to be supplied at the RCV2 pin.
Timing and trigger behaviour can also be influenced for
RCV2.
If there are missing pulses at RCV1 and/or RCV2, the time
base of DENC2 runs free, thus an arbitrary number of
synchronization slopes may miss, but no additional pulses
(such with wrong phase) must occur.
If the vertical and horizontal phase is derived from RCV1,
RCV2 can be used for horizontal or composite blanking
input or output.
In the master mode, the time base of the circuit
continuously runs free. On the RCV1 port, the IC can
output:
• A Vertical Sync signal (VS) with 3 or 2.5 lines duration,
or
• An ODD/EVEN signal which is LOW in odd fields, or
• A field sequence signal (FSEQ) which is HIGH in the first
of 4 respectively 8 fields.
On the RCV2 port, the IC can provide a horizontal pulse
with programmable start and stop phase; this pulse can be
inhibited in the vertical blanking period to build up e.g. a
composite blanking signal.
The phase of the pulses output on RCV1 or RCV2 are
referenced to the VP port, polarity of both signals is
selectable.
15
⁄16 with respect to Y
1996 Jul 088
Philips SemiconductorsPreliminary specification
Digital Video Encoder (DENC2)SAA7185
The DENC2 is always the timing master for the source at
the MP input. The IC provides two signals for
synchronizing this source:
On the RCM1 port the same signals as on RCV1 (as
output) are available; on RCM2 the IC provides a
horizontal pulse with programmable start and stop
phase.
The length of a field also start and end of its active part
can be programmed. The active part of a field always
starts at the beginning of a line.
Control interface
DENC2 contains two control interfaces: an I
transceiver and 8-bit parallel microprocessor interface.
The interfaces cannot be used simultaneously.
The I2C-bus interface is a standard slave transceiver,
supporting 7-bit slave addresses and 100 kbits/s
guaranteed transfer rate. It uses 8-bit subaddressing with
an auto-increment function. All registers are write only,
except one readable status byte.
Two I2C-bus slave addresses can be selected
(pin SEL_MPU must be LOW):
88H: LOW at pin 61
8CH: HIGH at pin 61.
2
C-bus slave
Input levels and formats
DENC2 expects digital YUV data with levels (digital codes)
in accordance with CCIR 601.
Deviating amplitudes of the colour difference signals can
be compensated by independent gain control setting,
while gain for luminance is set to predefined values,
distinguishable for 7.5 IRE set-up or without set-up.
The MPEG port accepts only 8-bit multiplexed CCIR 656
compatible data.
2
If the I
both formats, 8-bit multiplexed Cb-Y-Cr data on the
VP lines, or the 16-bit DTV2 format with the Y signal on the
VP lines and the UV signal on the DP port.
Reference levels are measured with a colour bar,
100% white, 100% amplitude and 100% saturation.
C-bus interface is used, the VP port can handle
The parallel interface is defined by:
D7 to D0 data bus
CS active-LOW chip select signal
RW read/not write signal, LOW for a write cycle
DTACK 680xx style data acknowledge (handshake),
active-LOW
A0 register select, LOW selects address, HIGH selects
data.
The parallel interface uses two registers, one
auto-incremental containing the current address of a
control register (equals subaddress with I2C-bus control),
one containing actual data. The currently addressed
register is mapped to the corresponding control register.
The status byte can be read optionally via a read access
to the address register, no other read access is provided.
1996 Jul 089
Philips SemiconductorsPreliminary specification
Digital Video Encoder (DENC2)SAA7185
Table 1 CCIR signal component levels
SIGNALIREDIGITAL LEVELCODE
016
Y
100235
bottom peak16
Cb
top peak240
bottom peak16
Cr
top peak240
Table 2 8-bit multiplexed format (similar to CCIR 656)