The MAX6957 compact, serial-interfaced LED display
driver general-purpose I/O (GPIO) peripheral provides
microprocessors with up to 28 ports. Each port is individually
user configurable to either a logic input, logic
output, or common-anode (CA) LED constant-current
segment driver. Each port configured as an LED segment
driver behaves as a digitally controlled constantcurrent
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.
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.
The MAX6957AAX and MAX6957ATL have 28 ports and
are available in 36-pin SSOP and 40-pin TQFN (6mm x
6mm) packages, respectively. The MAX6957AAI and
MAX6957ANI have 20 ports and are available in 28-pin
SSOP and 28-pin DIP packages, respectively.
For a 2-wire interfaced version, refer to the MAX6956
data sheet.
For a lower cost pin-compatible port expander without
the constant-current LED drive capability, refer to the
MAX7301 data sheet.
Key Features
Applications/Uses
High-Speed 26MHz SPI-/QSPI-™/MICROWIRE™-Compatible Serial Interface
2.5V to 5.5V Operation
-40°C to +125°C Temperature Range
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
11µA (max) Shutdown Current
16-Step Individually Programmable Current Control for Each LED
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