19-2429; Rev 0; 4/02
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
General Description
Features
The MAX6957 compact, serial-interfaced LED display
driver general-purpose I/O (GPIO) peripheral provides
microprocessors with up to 28 ports. Each port is indi-
vidually user configurable to either a logic input, logic
output, or common-anode (CA) LED constant-current
segment driver. Each port configured as an LED seg-
ment driver behaves as a digitally controlled constant-
current sink, with 16 equal current steps from 1.5mA to
24mA. The LED drivers are suitable for both discrete
LEDs and CA numeric and alphanumeric LED digits.
o High-Speed 26MHz SPI-/QSPI-™/MICROWIRE™-
Compatible Serial Interface
o 2.5V to 5.5V Operation
o -40°C to +125°C Temperature Range
o 20 or 28 I/O Ports, Each Configurable as
Constant-Current LED Driver
Push-Pull Logic Output
Schmitt Logic Input
Schmitt Logic Input with Internal Pullup
Each port configured as a GPIO can be either a push-
pull logic output capable of sinking 10mA and sourcing
4.5mA, or a Schmitt logic input with optional internal
pullup. Seven ports feature configurable transition
detection logic, which generates an interrupt upon
change of port logic level. The MAX6957 is controlled
through an SPI™-compatible 4-wire serial interface.
o 11µA (max) Shutdown Current
o 16-Step Individually Programmable Current
Control for Each LED
o Logic Transition Detection for Seven I/O Ports
The MAX6957AAX and MAX6957AGL have 28 ports and
are available in 36-pin SSOP and 40-pin QFN packages,
respectively. The MAX6957AAI and MAX6957ANI have
20 ports and are available in 28-pin SSOP and 28-pin DIP
packages, respectively.
Ordering Information
PART
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
28 DIP
MAX6957ANI
MAX6957AAI
MAX6957AAX
MAX6957AGL*
28 SSOP
36 SSOP
40 QFN
Applications
Set-Top Boxes
Panel Meters
*Future product—contact factory for availability.
Pin Configurations
White Goods
TOP VIEW
Automotive
Bar Graph Displays
Industrial Controllers
System Monitoring
ISET
GND
GND
DOUT
P12
1
2
3
4
5
6
7
8
9
28 V+
27 CS
DIN
26
25
SCLK
24 P31
23 P30
22 P29
21 P28
20 P27
19 P26
18 P25
17 P24
16 P23
15 P22
P13
P14
MAX6957
Typical Operating Circuit appears at end of data sheet.
P15
P16
P17 10
P18 11
P19 12
P20 13
P21 14
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
SSOP/DIP
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
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.