Analog Devices Inc./Maxim Integrated MAX6957ANI

Overview

MAX6957ANI from Maxim Integrated is a 20-port, 4-wire SPI-compatible LED display driver and GPIO expander in a 28-pin DIP package. It provides individually configurable ports as constant-current LED sinks (1.5–24mA, 16-step), push-pull logic outputs (10mA sink/4.5mA source), or Schmitt-trigger inputs with optional pullups. It supports transition detection on seven ports and operates from 2.5V to 5.5V across –40°C to +125°C - used in industrial panel meters and white goods UIs.

For engineers reviewing the MAX6957ANI datasheet, MAX6957ANI pinout, MAX6957ANI application, or MAX6957ANI equivalent, this page delivers verified port configuration logic, ISET resistor design guidance, shutdown current behavior (≤11µA), interrupt generation via P31, and real-world compatibility with 26MHz SPI/QSPI/MICROWIRE interfaces.

Technical Context

The MAX6957ANI implements a fixed-function serial peripheral architecture with no internal microcontroller core. Its 20 I/O ports (P4–P23) are mapped to registers 0x09–0x0D, and all unused ports (P24–P31) must be explicitly configured as outputs at power-up to avoid elevated quiescent current. The device uses a single external ISET resistor to set global LED current scaling, with per-port 4-bit intensity control available when global mode is disabled.

Its 4-wire interface (CS/SCLK/DIN/DOUT) operates synchronously with CS-active framing and 16-bit command/data words. DOUT echoes prior input data after 15.5 clocks and is never high-impedance - requiring external tri-state conversion if shared bus operation is needed. Transition detection is implemented as a hardware comparator snapshot of P24–P30 against a maskable register, latching P31 high until the mask register is accessed.

Key Specifications

Pinout & Package

MAX6957ANI is housed in a 28-pin plastic dual in-line package (PDIP) with 0.6-inch body width and 0.1-inch lead pitch. Pin 1 is marked by a notch or dot; pins 2–3 and 25–28 align with standard 28-DIP footprints. Thermal performance is rated at 1143mW at +70°C with 14.3mW/°C derating above that.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6956AAX and MAX7301ATG+, the MAX6957ANI uniquely combines high-speed SPI interfacing, per-port LED current control, and hardware interrupt generation - making it the only choice for cost-sensitive, space-constrained designs needing both display driving and robust input monitoring in one IC.

Availability

MAX6957ANI is available at Aetrix Electronics and suitable for industrial controllers, panel meters, and white goods requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6957ANI 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, mixed-signal, and power management ICs for industrial, automotive, and communications applications.

The MAX6957 product line targets embedded human-machine interface (HMI) subsystems, delivering integrated LED driving and GPIO expansion to simplify front-panel design in harsh-environment equipment.

FAQ

What is the correct power-up sequence for MAX6957ANI?

On initial power-up, MAX6957ANI enters shutdown mode with all ports as Schmitt inputs. To enable operation, write '0' to the S bit (bit 7) of the configuration register (0x04). Additionally, write 0x55 to registers 0x09 and 0x0A to configure unused ports P24–P31 as outputs - preventing elevated supply current caused by floating inputs. This initialization must occur before configuring LED currents or GPIO directions.

How do I set the LED segment current on MAX6957ANI?

MAX6957ANI uses an external resistor (RISET) between ISET (pin 1) and GND to set maximum LED current. With RISET = 39kΩ, full-scale current is ~24mA at V+ = 5.5V. Each port's actual current is then scaled digitally via 4-bit intensity registers (0x12–0x1F) or globally via register 0x02. The MAX6957ANI datasheet Table 12 provides exact current values per code and supply voltage.

Can MAX6957ANI drive common-cathode (CC) LED displays?

No - MAX6957ANI is designed exclusively for common-anode (CA) LED configurations. Its ports operate as constant-current sinks, turning on a CA segment when driven low. Driving CC displays would require sourcing current, which the MAX6957ANI does not support. For CC applications, consider discrete transistor arrays or dedicated CC drivers like the MAX6966.

What happens to port states during MAX6957ANI shutdown mode?

During shutdown, all MAX6957ANI ports are forced to high-impedance Schmitt inputs, and internal pullup current sources are disabled. However, register contents - including port configuration, intensity settings, and mask registers - remain intact. When exit shutdown (S bit = 1), the MAX6957ANI restores prior port states and drive modes without reinitialization, preserving system context.

Is MAX6957ANI pin-compatible with other MAX6957 variants?

No - MAX6957ANI (28-pin DIP) is not pin-compatible with MAX6957AAI (28-pin SSOP), MAX6957AAX (36-pin SSOP), or MAX6957ATL (40-pin TQFN). While all share identical register maps and functional behavior, their pin counts, layouts, and port mappings differ. Specifically, MAX6957ANI exposes only P4–P23 (20 ports); P24–P31 are physically absent and must be software-disabled per datasheet guidance.