General Description
The MAX6972/MAX6973 precision current-sinking,
16-output PWM LED drivers drive red, green, and/or blue
LEDs for full-color graphic message boards and video
displays. Each output has an individual 12-bit (MAX6972)
or 14-bit (MAX6973) PWM-intensity (hue) control and
7-bit (MAX6972) or 5-bit (MAX6973) global PWM intensity
(luminance) control. The MAX6972/MAX6973 also feature open-circuit LED fault-detection circuitry, as well as
a watchdog timer.
The driver has two banks of eight outputs, with each bank
intended to drive a different color in RGB applications.
The standard application uses three MAX6972/
MAX6973s to drive eight RGB LEDs. The full-scale current
for each bank of eight outputs is adjustable from 11mA
to 55mA in 256 steps (0.3125% per step) to calibrate
each color.
The MAX6972/MAX6973 can optionally multiplex by
using outputs MUX0 and MUX1, which each drive an
external pnp transistor. Multiplexing doubles the
MAX6972/MAX6973 drive capability to 32 LEDs.
The MAX6972/MAX6973 operate from a 3.0V to 3.6V
power supply. The LED power supply can range from
3V to 7V. The LED drivers require only 0.8V headroom
above the LEDs’ forward-voltage drop. Using a separate LED supply voltage for each LED minimizes power
consumption.
The serial interface uses differential signaling for the
high-speed clock and data signals to reduce EMI and
improve signal integrity. The MAX6972/MAX6973 buffer
all interface signals to simplify cascading devices in
modules that use a large number of drivers.
An internal watchdog timer, when enabled, automatically
clears the pixel-data registers and blanks the display if
any of the signal inputs fail to toggle within 40ms.
The MAX6972/MAX6973 are available in 32-pin TQFN
packages and operate over the -40°C to +125°C
temperature range.
Refer to the MAX6974/MAX6975 data sheet for a
24-output, 6mA to 30mA software-compatible device.
EZCascade is a trademark of Maxim Integrated Products, Inc.
Applications
LED Video Display Panels
LED Message Boards
Variable Message Signs (VMS)
Signs
Graphic Panels
Features
♦ 16 LED Current Sink Outputs (Two Banks of Eight
Outputs)
♦ 32 LED Drive Option When Multiplexing
♦ 33MHz Clock Supports Up to 63 Frames per
Second of Video
♦ Constant Output Current Calibration from 11mA
to 55mA in 256 Steps
♦ EZCascade™ Interface Simplifies Multiple Driver
Cascading Without External Buffers
♦ 12-Bit or 14-Bit Individual PWM LED Intensity
Controls
♦ 7-Bit or 5-Bit Panel PWM-Intensity Control
♦ +3V to +7V LED Power Supply
♦ +3.0V to +3.6V Logic Supply
♦ Open-Circuit LED Fault Detection
♦ Optional Watchdog Timer Blanks Display if
Interface Fails
♦ Standard -40°C to +125°C Operating Temperature
Range
MAX6972/MAX6973
16-Output PWM LED Drivers
for Message Boards
________________________________________________________________ Maxim Integrated Products 1
MAX6972ATJ
MAX6973ATJ
TQFN
5mm x 5mm
TOP VIEW
29
30
28
27
12
11
13
MUX0
CLKI-
DIN+
DIN-
LOADI
14
V
DD
MUX1
CLKO-
DOUT+
AGND
DOUT-
LOAD0
1+2
Z4
4567
2324 22 20 19 18
Z3
Z2
Y5
Y4
Y3
Y2
CLKI+
CLKO+
3
21
31
10
Z1
Y1
32
9
Z0
Y0
Z5
26
15
Y6
Z6
25
16
Y7
EP*
*EP = EXPOSED PADDLE.
I.C.
V
DD
8
17
Z7
Pin Configuration
Ordering Information
19-0534; Rev 0; 5/06
For pricing delivery, and ordering information please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Typical Operating Circuit appears at the end of data sheet.
*EP = Exposed paddle.
+Denotes lead-free package.
-40°C to +125°C 32 TQFN-EP*
-40°C to +125°C 32 TQFN-EP*
MAX6972/MAX6973
16-Output PWM LED Drivers
for Message Boards
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.
(All voltages with respect to GND.)
V
DD
........................................................................-0.3V to +4.0V
Y0–Y7, Z0–Z7, MUX0, and MUX1 .........................-0.3V to +8.0V
All Other Pins..............................................-0.3V to (V
DD
+ 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
32-Pin TQFN (derate 34.5mW/°C over +70°C) ..........2857mW
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Operating Supply Voltage V
DD
V
O
7V
f
CLKI
= 0Hz; CLKO_, DOUT_ loaded 200Ω;
calibration DACs set to 0x01
f
CLKI
= 0Hz; CLKO_, DOUT_ loaded 200Ω;
calibration DACs set to 0xFF
Supply Current I
DD
f
CLKI
= 32MHz; CLKO_, DOUT_ loaded 200Ω;
calibration DACs set to 0xFF
Input High Voltage LOADI V
IHC
0.7
V
Input Low Voltage LOADI V
ILC
V
Differential Input Voltage Range
CLKI_, DIN_
V
ID
V
Common-Mode Input Voltage
CLKI_, DIN_
V
CM
V
Differential Input High Threshold
Differential Input Low Threshold
Differential Output Voltage
CLKO_, DOUT_
V
OD
Termination 200Ω at receiver _+ and _- inputs
Differential Output Offset
CLKO_, DOUT_
V
OS
Termination 200Ω at receiver _+ and _- inputs
V
Input Leakage Current
CLKI_, DIN_, LOADI
I
IH
, I
IL
-1
µA
Input Capacitance
CLKI_, DIN_, LOADI
pF
Output Low Voltage LOADO V
OLCISINK
= 5mA
V
Output High Voltage LOADO V
OHC
I
SOURCE
= 5mA
V
DD
- 0.5
V
Output Slew Time LOADO 20% to 80%, 80% to 20%, load = 10pF 3 ns
ELECTRICAL CHARACTERISTICS
(VDD= 3.0V to 3.6V, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at VDD= 3.3V, TA= +85°C.) (Note 1)
(Y0–Y7, Z0–Z7, MUX0, and MUX1)
SYMBOL
MIN TYP MAX
3.0 3.6
VDIFF
TH
VDIFF
TL
x V
±0.15 ±1.20
| V
I D
-65
±190 ±550
1.125 1.25 1.375
21 35
40 55
42 60
DD
/ 2| 2.4
10
0.05 0.25
V
DD
- 0.2
0.3
x V
DD
65
+1
MAX6972/MAX6973
16-Output PWM LED Drivers
for Message Boards
_______________________________________________________________________________________ 3
Note 1: All parameters tested at TA= +85°C. Specifications over temperature are guaranteed by design.
Note 2: Specification limits apply to devices at the same T
A
for TA= T
MIN
to T
MAX
.
Note 3: Guaranteed by design.
Output Low Voltage MUX_ V
OLMISINK
= 40mA
V
Open-Circuit Detection V
OCD
Output Slew Time
Y0–Y7, Z0–Z7
80% to 20%, load = 50pF,
calibration DACs set to 0xFF
Full-Scale Port Output Current
Y0–Y7, Z0–Z7
Port-to-Port Current Matching
Y0–Y7, Z0–Z7
I
SINK
= 55mA (Note 2)
T
A
= -40°C
(Note 3)
%
D evi ce- to- D evi ce C ur r ent M atchi ng
Y0–Y7, Z0–Z7
∆I
AVG
I
SINK
= 55mA, TA = +85°C (Note 3)
Half-Scale Port Output Current
Y0–Y7, Z0–Z7
Output Load Regulation ∆I
OLR
V
D D
= 3.3V , V O = 1.2V to
3.0V , calibration DACs set to
0x80, I
SINK
= 33mA
Output Power-Supply Rejection
V
D D
= 3.0 V to 3.6V ,
V
O
= 1.2V , calibration DACs
set to 0x80, I
SINK
= 33mA
ELECTRICAL CHARACTERISTICS (continued)
(VDD= 3.0V to 3.6V, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at VDD= 3.3V, TA= +85°C.) (Note 1)
CLKI_ Input Frequency f
CLKI
8ns
Watchdog Period When enabled 40
TIMING CHARACTERISTICS
(VDD= 3.0V to 3.6V, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at 3.3V, TA= +85°C.) (Note 1)
SYMBOL
I
SINKFS
∆I
SINK
I
SINKHS
∆I
OPSR
calibration DACs set to 0xFF
calibration DACs set to 0xFF
V
= 3.3V , V O = 1.2V , cal i b r ati on D AC s set to 0xFF,
D D
calibration DACs set to 0x80
T
= T
A
T
= T
A
TA = T
TA = T
MIN
MIN
MIN
MIN
to T
to T
to T
to T
MIN TYP MAX
52.5 55 58.0
MAX
31.0 33 35.5
30.0 33 36.5
MAX
MAX
MAX
0.4
200
100
55 56
±0.5 ±1.8
±0.5 ±1.2
±0.7 ±2.3
±1 ±2
0.3 1.15
1.5
0.6 1.7
2.0
SYMBOL
t
PD-CLKO
t
SU-DIN
t
HD-DIN
t
PD-DOUT
t
PD-LOADO
t
SU-LOADI
t
HD-LOADI
MIN TYP MAX
33
60
16
0.5
15
18
125 300
MAX6972/MAX6973
16-Output PWM LED Drivers
for Message Boards
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VDD= 3.3V, TA= +25°C, unless otherwise noted.)
OPERATING CURRENT CONSUMPTION
vs. SUPPLY VOLTAGE V
DD
MAX6972/73 toc01
SUPPLY VOLTAGE VDD (V)
I
DD
(mA)
3.53.43.33.23.1
41
43
45
47
39
3.0 3.6
TA = -40°C
f
CLKI
= 32MHz
CALDAC = 0xFF
TA = +25°C
TA = +85°C
TA = +125°C
OPERATING CURRENT CONSUMPTION
vs. SUPPLY VOLTAGE V
DD
MAX6972/73 toc02
SUPPLY VOLTAGE VDD (V)
I
DD
(mA)
3.53.43.33.23.1
19
21
23
25
15
17
3.0 3.6
TA = -40°C
TA = +25°C
TA = +85°C
TA = +125°C
f
CLKI
= 0MHz
CALDAC = 0x00
LED OUTPUT SINK CURRENT
vs. OUTPUT VOLTAGE
MAX6972/73 toc03
OUTPUT VOLTAGE (V)
I
SINK
(mA)
54321
20
50
60
30
40
70
0
10
067
TA = -40°C
TA = +25°C
TA = +85°C
TA = +125°C
LED OUTPUT SINK CURRENT
vs. OUTPUT VOLTAGE
MAX6972/73 toc04
OUTPUT VOLTAGE (V)
I
SINK
(mA)
54321
20
50
60
30
40
70
0
10
067
VDD = +3.0V
VDD = +3.3V
VDD = +3.6V
MAX6972/MAX6973
16-Output PWM LED Drivers
for Message Boards
_______________________________________________________________________________________ 5
Pin Description
PIN NAME FUNCTION
1,17 V
DD
Positive Supply Voltage. Bypass VDD to GND with a 0.1µF ceramic capacitor.
2 MUX0 Multiplex 0 Active-Low, Open-Drain Output. Use MUX0 to drive a pnp transistor.
3 CLKI+ PWM and Serial-Interface Noninverting Clock LVDS Input
4 CLKI- PWM and Serial-Interface Inverting Clock LVDS Input
5 DIN+ Serial-Interface Noninverting Data LVDS Input
6 DIN- Serial-Interface Inverting Data LVDS Input
7 LOADI Serial-Interface Load CMOS Input
8 I.C. Internally Connected. Connect to GND.
9–16 Y0–Y7 Y LED Drive Outputs. Y0 to Y7 are open-drain, constant-current sinks.
18 LOADO Serial-Interface Load CMOS Output
19 DOUT- Serial-Interface Inverting Data LVDS Output
20 DOUT+ Serial-Interface Noninverting Data LVDS Output
21 CLKO- PWM and Serial-Interface Inverting Clock LVDS Output
22 CLKO+ PWM and Serial-Interface Noninverting Clock LVDS Output
23 MUX1 Multiplex 1 Active-Low, Open-Drain Output. Use MUX1 to drive a pnp transistor.
24 AGND Analog Ground. Connect to GND.
25–32 Z7–Z0 Z LED Drive Outputs. Z0 to Z7 are open-drain, constant-current sinks.
EP GND Power Ground. Exposed pad on package underside must be connected to GND.
MAX6972/MAX6973
16-Output PWM LED Drivers
for Message Boards
6 _______________________________________________________________________________________
MAX6972 Block Diagram
MUX1
OUTPUT
MUX0
OUTPUT
Y LED DRIVERS
Y7–Y0
I
SET
EXT. PNP
8-BIT
Y CALDAC
Z LED DRIVERS
Z0–Z7
CALIBRATION
DATA LATCH
GLOBAL-
INTENSITY
DATA LATCH
PWM
COUNTERS
SYNC
CONTROL
SYNC DETECT
24-BIT NEW HEADER
SHIFT REGISTER
7-BIT GLOBAL-INTENSITY FRAME MODULATOR
12-BIT INDIVIDUAL INPUT MODULATOR
8
I
SET
8-BIT
Z CALDAC
Y LED OUTPUT
Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0
Z LED OUTPUT
Z7 Z6 Z5 Z4 Z3 Z2 Z1 Z0
8
8
0/1
8
7
7
192
192 192
192 192
192
192
192
16
7
MUX0 PIXEL PWM OLD DATA LATCH MUX1 PIXEL PWM OLD DATA LATCH
LOAD
OE
LOAD
OE
MUX0 PIXEL PWM NEW DATA LATCH MUX1 PIXEL PWM NEW DATA LATCH
192-BIT DATA SHIFT REGISTER
EN
CLKI
DIN
EN
DOUT
CLKO
LOADO
D
Q1
LOADI
EXT. PNP
MAX6972
MAX6972/MAX6973
16-Output PWM LED Drivers
for Message Boards
_______________________________________________________________________________________ 7
MAX6973 Block Diagram
MUX1
OUTPUT
MUX0
OUTPUT
Y LED DRIVERS
Y7–Y0
I
SET
EXT. PNP
8-BIT
Y CALDAC
Z LED DRIVERS
Z0–Z7
CALIBRATION
DATA LATCH
GLOBAL-
INTENSITY
DATA LATCH
PWM
COUNTERS
SYNC
CONTROL
SYNC DETECT
24-BIT NEW HEADER
SHIFT REGISTER
5/3-BIT GLOBAL-INTENSITY PDM MODULATOR
14-BIT INDIVIDUAL PWM MODULATOR
8
I
SET
8-BIT
Z CALDAC
Y LED OUTPUT
Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0
Z LED OUTPUT
Z7 Z6 Z5 Z4 Z3 Z2 Z1 Z0
8
8
0/1
8
5
5
224
224 224
224 224
224
224
224
16
5
MUX0 PIXEL PWM OLD DATA LATCH MUX1 PIXEL PWM OLD DATA LATCH
LOAD
OE
LOAD
OE
MUX0 PIXEL PWM NEW DATA LATCH MUX1 PIXEL PWM NEW DATA LATCH
224-BIT DATA SHIFT REGISTER
EN
CLKI
DIN
EN
DOUT
CLKO
LOADO
D
Q1
LOADI
EXT. PNP
MAX6973