Analog Devices Inc./Maxim Integrated MAX6957AAX/GH9

Overview

The MAX6957AAX/GH9 from Maxim Integrated is a 28-port, SPI-compatible LED display driver and GPIO expander with individually configurable ports (P4–P31), 16-step programmable constant-current LED sink (1.5mA–24mA per port), 2.5V–5.5V operation, and −40°C to +125°C temperature range-designed for driving common-anode numeric/alphanumeric LED displays and providing logic I/O in industrial panel meters and automotive instrument clusters.

For engineers reviewing the MAX6957AAX/GH9 datasheet, MAX6957AAX/GH9 pinout, MAX6957AAX/GH9 application, or MAX6957AAX/GH9 equivalent, key selection considerations include its 36-pin SSOP package, 26MHz SPI interface timing, transition-detection interrupt on P31, and dual-mode port configuration (LED driver vs. push-pull/Schmitt GPIO).

Technical Context

The MAX6957AAX/GH9 implements a 4-wire SPI-compatible serial interface (CS, SCLK, DIN, DOUT) with 16-bit command/data framing, supporting daisy-chained configurations. Its 28 I/O ports (P4–P31) are configured via dedicated registers (0x09–0x0F), each pair of bits selecting one of four modes: LED segment driver, push-pull output, Schmitt input, or Schmitt input with internal pullup.

LED current is set globally (register 0x02) or per-port (registers 0x12–0x1F), with 16 equal steps across 1.5mA–24mA. Transition detection is implemented on ports P24–P30 using a maskable 7-bit snapshot comparator, with interrupt output asserted on P31-a dedicated active-high INT signal requiring P31 to be configured as output.

Key Specifications

Pinout & Package

The MAX6957AAX/GH9 is housed in a 36-pin SSOP (shrink small-outline package) with exposed paddle (EP) internally connected to GND for thermal management. Pin 1 is ISET; pins 2–3 and 37–39 are GND; pin 40 is DOUT; pins 5–24 map to P12–P31; pins 25–28 are SCLK, DIN, CS, and V+; pins 11, 20, and 31 are no-connect (N.C.).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED display driver and I/O expander applications.

Compared with MAX6956ATL+, the MAX6957AAX/GH9 offers hardware-based transition detection and faster SPI throughput; compared with MAX7301ATG+, it integrates precision LED current control-eliminating external resistors and enabling unified display/I/O management in a single chip.

Availability

MAX6957AAX/GH9 is available at Aetrix Electronics and suitable for automotive instrument clusters, industrial panel meters, white goods control panels, and set-top box front panels requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6957AAX/GH9 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, and communications applications.

The MAX6957 product line delivers integrated LED display drivers with GPIO expansion, targeting applications demanding compact, thermally robust solutions for driving common-anode displays while minimizing external components and MCU overhead.

FAQ

What is the maximum LED segment current supported by the MAX6957AAX/GH9?

The MAX6957AAX/GH9 supports a maximum LED sink current of 24mA per port when configured as a constant-current LED driver, set by the ISET resistor (e.g., 39kΩ to GND yields 24mA at V+ = 5.5V). This value is confirmed in the Electrical Characteristics table under "Port Drive LED Sink Current" and applies across the full −40°C to +125°C operating range.

How many I/O ports does the MAX6957AAX/GH9 provide, and what are their default states at power-up?

The MAX6957AAX/GH9 provides 28 I/O ports (P4 through P31) in its 36-pin SSOP package. At power-up, all ports default to Schmitt logic inputs with no internal pullup enabled, and the device enters shutdown mode-requiring configuration via SPI to activate ports as LED drivers or GPIO outputs before use.

Does the MAX6957AAX/GH9 support daisy-chaining, and how is it implemented?

Yes, the MAX6957AAX/GH9 supports daisy-chaining via its DOUT pin, which echoes DIN data after a 15.5-clock delay. Multiple devices are connected by routing DOUT of one to DIN of the next, with shared SCLK and CS lines. A 16-bit write to n devices requires 16×n clock cycles, and individual device updates use the No-Op command (0x00) to idle non-target units.

What is the function of pin P31 on the MAX6957AAX/GH9, and how is it configured for interrupt use?

Pin P31 on the MAX6957AAX/GH9 serves as the active-high interrupt output (INT) for transition detection. To enable it, P31 must be configured as a push-pull output (bits D7=0, D6=1 in port configuration register 0x0F), and transition detection must be activated by setting the M bit in the configuration register (0x04); detected changes on P24–P30 then assert P31 high until the mask register is accessed.

Can the MAX6957AAX/GH9 drive both discrete LEDs and common-anode (CA) numeric digits?

Yes, the MAX6957AAX/GH9 is explicitly designed to drive both discrete LEDs and common-anode numeric/alphanumeric digits-including seven-segment, starburst, and 16-segment+DP types. Its constant-current sink architecture ensures uniform brightness across segments regardless of forward voltage variation, and its port mapping supports flexible digit segmentation schemes.