Analog Devices Inc./Maxim Integrated MAX6957ATL+T

Overview

MAX6957ATL+T from Maxim Integrated is a 28-port, SPI-compatible LED display driver and GPIO expander in a 40-pin TQFN-EP package. It provides individually configurable ports (P4–P31) as constant-current LED sinks (1.5–24mA, 16-step), push-pull outputs (10mA sink/4.5mA source), or Schmitt inputs with optional pullup - enabling mixed-signal control in compact industrial displays and panel meters.

For engineers reviewing the MAX6957ATL+T datasheet, MAX6957ATL+T pinout, MAX6957ATL+T application, or MAX6957ATL+T equivalent, this device supports high-speed (26MHz) 4-wire serial interfacing, operates from 2.5V to 5.5V across –40°C to +125°C, and integrates transition-detection interrupts on seven ports for real-time status monitoring without host polling.

Technical Context

The MAX6957ATL+T implements a fully synchronous SPI-compatible interface with CS, SCLK, DIN, and DOUT lines - supporting daisy-chaining via DOUT-to-DIN propagation (15.5-clock delay). Its register architecture enables per-port configuration (LED/GPIO input/output) via 7-bit command addresses and 8-bit data writes, with virtual port addressing (P0–P3) for seamless multi-device digit overlap handling.

It features dual current control modes: global (single register 0x02) or individual (registers 0x12–0x1F, nibble-per-port), with ISET resistor (RISET = 39kΩ typical) setting maximum segment current. Transition detection logic monitors P24–P30 against a snapshot register, latching interrupt on P31 until mask register access clears it - a one-shot, non-continuous event.

Key Specifications

Pinout & Package

MAX6957ATL+T uses a 40-pin TQFN-EP (6mm × 6mm) package with exposed pad internally connected to GND for thermal dissipation. Pin numbering follows standard top-view layout with pin 1 at top-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6956ATL+T, the MAX6957ATL+T delivers 65× faster serial throughput and native daisy-chain support; compared with MAX7301ATG+T, it integrates precision LED driving - eliminating external components but increasing supply current by ~100µA in active LED mode.

Availability

MAX6957ATL+T is available at Aetrix Electronics and suitable for industrial controllers, panel meters, and set-top boxes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6957ATL+T 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) designs high-performance analog and mixed-signal ICs for industrial, automotive, and communications applications.

The MAX6957ATL+T belongs to Maxim's LED display driver and I/O expander product line, engineered to consolidate display control and digital interfacing into a single robust device for harsh-environment human-machine interfaces.

FAQ

What is the maximum LED segment current supported by the MAX6957ATL+T?

The MAX6957ATL+T supports a maximum LED sink current of 24mA per segment when configured as a constant-current driver, set by the external ISET resistor (e.g., 39kΩ for 24mA at V+ = 5.5V). This value is digitally adjustable in 16 equal steps from 1.5mA to 24mA, with matching accuracy of ±6% between ports.

Does the MAX6957ATL+T support daisy-chaining with other MAX6957 devices?

Yes, the MAX6957ATL+T supports daisy-chaining via its DOUT pin connected to the DIN of the next device. Data propagates with a 15.5-clock delay, and commands to n devices require (16 × n) SCLK cycles. The MAX6957ATL+T does not require address decoding - all devices in the chain execute the same command unless masked with No-Op (0x00).

How is interrupt generation implemented on the MAX6957ATL+T?

The MAX6957ATL+T generates an interrupt on port P31 when a logic-level transition is detected on any of ports P24–P30, provided those ports are enabled in the transition detection mask register. The interrupt is latched high and cleared only by reading or writing the mask register - it is a one-shot event requiring explicit software acknowledgment.

Can the MAX6957ATL+T drive common-anode (CA) LED digits directly?

Yes, the MAX6957ATL+T is explicitly designed to drive common-anode LED digits. Each port configured as an LED driver acts as a digitally controlled constant-current sink, turning on a CA segment when driven low. It supports 7-segment, 14-segment, 16-segment, and starburst alphanumeric digits without external transistors or current-setting resistors.

What is the function of the ISET pin on the MAX6957ATL+T?

The ISET pin on the MAX6957ATL+T sets the maximum LED segment current by connecting it to GND through a precision resistor (RISET). For example, a 39kΩ resistor yields ~24mA maximum current at V+ = 5.5V. The actual current per port is then scaled digitally in 16 steps from 1/16 to 16/16 of this maximum value.