Analog Devices Inc./Maxim Integrated MAX7301ANI+

Overview

The MAX7301ANI+ from Maxim Integrated is a 4-wire SPI-compatible 20-port GPIO expander operating from 2.5V to 5.5V, supporting industrial temperature range (−40°C to +125°C), delivering up to 10mA sink and 4.5mA source per port, with Schmitt-trigger inputs and internal pullups - used in white goods control panels for button/LED interface expansion.

For engineers reviewing the MAX7301ANI+ datasheet, MAX7301ANI+ pinout, MAX7301ANI+ application, or MAX7301ANI+ equivalent, this page delivers verified electrical specs, DIP-28 package mapping, transition-detection interrupt behavior on P31, and real-world substitution guidance for embedded I/O expansion designs.

Technical Context

The MAX7301ANI+ implements a 16-bit SPI-compatible serial interface with fixed 4-wire protocol (CS, SCLK, DIN, DOUT), no tri-state DOUT, and daisy-chain capability via 15.5-clock-cycle data propagation. It supports register-based configuration of all 20 I/O ports (P12–P31) as push-pull outputs or Schmitt inputs with individually enabled pullups.

Transition detection is hardware-asserted on port P31 (INT) for any combination of P24–P30, using a maskable 7-bit snapshot register; detection is one-shot and cleared only by reading/writing the mask register. Shutdown mode forces all ports to high-impedance inputs while preserving register state.

Key Specifications

Pinout & Package

MAX7301ANI+ uses a 28-pin dual in-line package (DIP) with through-hole mounting. Pin 1 is marked with a notch or dot; pin numbering follows standard DIP convention (counter-clockwise from notch).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX7301ANI+, MAX7300AUI+ trades SPI speed and daisy-chain flexibility for I²C simplicity, while MAX6957AUI+ adds LED-specific features at the cost of package compatibility and increased complexity - neither is pin-compatible, but both serve adjacent functional niches in Maxim's portfolio.

Availability

MAX7301ANI+ is available at Aetrix Electronics and suitable for white goods control panels, industrial PLC I/O expansion, and automotive body controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX7301ANI+ 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 high reliability and wide operating ranges.

The MAX7301 series was developed to provide robust, low-pin-count GPIO expansion for resource-constrained microcontrollers in harsh environments - prioritizing SPI simplicity, interrupt efficiency, and thermal resilience over feature bloat.

FAQ

What is the exact I/O port count and mapping for MAX7301ANI+?

The MAX7301ANI+ provides exactly 20 GPIO ports: P12 through P31. Ports P4–P11 are physically unconnected in the 28-pin DIP package and must be configured as outputs at power-up (by writing 0x55 to registers 0x09 and 0x0A) to prevent elevated quiescent current. This mapping is fixed and differs from the 28-port MAX7301AAX variant.

Does MAX7301ANI+ support true tri-state DOUT for bus sharing?

No, MAX7301ANI+ DOUT is never high-impedance - it continuously outputs data or echoes prior commands. To share a serial bus with other devices, external tri-state buffering (e.g., using a 74LVC1G125) is required. Maxim Application Note AN1879 documents proven methods for converting DOUT to tri-state behavior.

How does transition detection work on MAX7301ANI+ and which ports support it?

Transition detection on MAX7301ANI+ monitors ports P24–P30 for logic-level changes and asserts an active-high interrupt on P31. Detection is enabled by setting the M bit in the configuration register, which captures a 7-bit snapshot; any subsequent change on a masked port latches P31 high until the mask register is read or written - a one-shot mechanism requiring explicit clearing.

What is the purpose of the ISET pin on MAX7301ANI+ and what resistor value is required?

The ISET pin on MAX7301ANI+ sets internal bias current via an external resistor to GND. A 39kΩ resistor is specified in the datasheet to ensure correct operation of internal references and timing circuits. Using values outside 39kΩ–120kΩ may cause undefined behavior in output drive strength or shutdown current.

Can MAX7301ANI+ operate below 2.5V, and what are the trade-offs?

MAX7301ANI+ can function down to 2.0V supply after initial power-up at ≥2.5V (to trigger internal reset), but output drive strength (sink/source current) and timing parameters (e.g., 26MHz max clock) are not guaranteed below 2.5V. SPI communication must be limited to ≤10Mbps in sub-2.5V operation per the Applications Information section.