Analog Devices Inc./Maxim Integrated MAX6957AGL+

Overview

MAX6957AGL+ from Maxim Integrated is a 4-wire SPI-compatible LED display driver and I/O expander with 28 configurable ports (P4–P31), operating from 2.5V to 5.5V, supporting -40°C to +125°C industrial temperature range, delivering up to 24mA per LED segment with 16-step current control, and enabling logic input/output or constant-current sink functionality per port - used in panel meters and industrial controllers for mixed-segment LED and GPIO management.

For engineers reviewing the MAX6957AGL+ datasheet, MAX6957AGL+ pinout, MAX6957AGL+ application, or MAX6957AGL+ equivalent, this page delivers verified electrical specs, confirmed 40-pin TQFN-EP package mapping, validated 28-port configuration logic, real-world transition-detection interrupt behavior on P31, and precise current-setting resistor (ISET) interface design guidance.

Technical Context

The MAX6957AGL+ implements an SPI-compatible 4-wire serial interface (CS, SCLK, DIN, DOUT) with 26MHz max clock rate, 38.4ns minimum clock period, and deterministic 15.5-cycle data latency for daisy-chaining. Its internal architecture supports dual-mode port control: each of the 28 ports (P4–P31) is individually configured via 2-bit register fields (0x09–0x0F) as LED driver (open-drain sink), push-pull output (10mA sink / 4.5mA source), or Schmitt input (with optional pullup).

Transition detection is hardware-accelerated for ports P24–P30 only, using a snapshot-and-compare mechanism that latches P31 high on change and requires mask-register access to clear; LED current is set globally (0x02) or per-port (0x12–0x1F) via 4-bit nibbles, with ISET resistor (e.g., 39kΩ) defining full-scale 24mA at V+ = 5.5V and VLED = 2.4V.

Key Specifications

Pinout & Package

MAX6957AGL+ is housed in a 40-pin TQFN-EP (6mm × 6mm) package with exposed pad internally connected to GND. Thermal performance requires soldering the EP to a large ground plane; it is not a standalone ground connection.

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+, MAX6957AGL+ provides higher-speed SPI updates and avoids I²C address conflicts; compared with MAX7301ATG+, it adds essential LED current regulation but increases complexity for pure GPIO use cases.

Availability

MAX6957AGL+ is available at Aetrix Electronics and suitable for panel meters, industrial controllers, and white goods requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6957AGL+ 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 precision analog and mixed-signal ICs for industrial, automotive, and communications applications, emphasizing robustness, integration, and low-power operation.

The MAX6957AGL+ belongs to Maxim's LED display driver and I/O expander product line, engineered to consolidate display control and general-purpose digital I/O into a single chip for space-constrained, thermally demanding human-machine interface applications.

FAQ

What is the package type and pin count for MAX6957AGL+?

MAX6957AGL+ uses a 40-pin TQFN-EP (6mm × 6mm) package with exposed pad. It provides all 28 I/O ports (P4–P31) in this variant - unlike the 28-pin SSOP/DIP versions which offer only 20 ports. The exposed pad must be soldered to a large ground plane for thermal dissipation and electrical stability.

How does the MAX6957AGL+ configure its 28 ports between LED driving and GPIO functions?

MAX6957AGL+ configures each port (P4–P31) independently via two-bit fields in registers 0x09 through 0x0F. A '00' code sets the port as a constant-current LED sink (1.5–24mA); '01' configures it as a push-pull logic output; '10' or '11' selects Schmitt input with or without internal pullup. Configuration persists through power cycles unless rewritten.

What is the role of the ISET pin on the MAX6957AGL+ and how is it used?

The ISET pin (Pin 40) on MAX6957AGL+ connects to GND through a precision resistor (e.g., 39kΩ) to set the maximum LED segment current. This resistor defines full-scale current - 24mA at V+ = 5.5V and VLED = 2.4V - and scales all 16 current steps proportionally. No external DAC or voltage reference is required.

Can the MAX6957AGL+ generate interrupts, and if so, how is that implemented?

Yes, MAX6957AGL+ generates interrupts via port P31 when logic transitions occur on any enabled subset of ports P24–P30. Transition detection is controlled by the mask register (0x06); a detected change latches P31 high until the mask register is read or written - no software polling is needed for edge detection.

Does the MAX6957AGL+ support daisy-chaining, and what is required to implement it?

Yes, MAX6957AGL+ supports daisy-chaining via its DOUT-to-DIN connection topology. All devices share SCLK and CS lines; data propagates with 15.5-clock latency. To address individual units, send No-Op commands (0x00) to non-target devices while sending valid 16-bit commands to the intended unit - requiring (16 × n) clocks for n devices.