Rainbow Electronics MAX6973 - Manual

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 fea-
ture 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 sepa-
rate 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
4 5 6 7
23 24 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.
PART TEMP RANGE
PIN-
PACKAGE PKG
CODE
MAX6972ATJ+ -40°C to +125°C 32 TQFN-EP* T3255-5
MAX6973ATJ+ -40°C to +125°C 32 TQFN-EP* T3255-5
Typical Operating Circuit appears at the end of data sheet.
*EP = Exposed paddle.
+Denotes lead-free package.