4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and 28-Port LED Display Driver and I/O Expander

 

Part Number	Replacement	Explanation

Description

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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.

MAX6957: Typical Operating Circuit Enlarge+

Key Features

• 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
• Logic Transition Detection for Seven I/O Ports

Applications/Uses

• Bar Graph Displays
• Industrial Controllers
• Panel Meters
• Set-Top Boxes
• System Monitoring
• White Goods