Analog Devices Inc./Maxim Integrated MAX7359ETG+T

Overview

MAX7359ETG+T from Maxim Integrated is a 2-wire (I²C) interfaced key switch controller that manages up to 64 mechanical or resistive keys with static matrix scanning, 16-entry FIFO buffering, and configurable autosleep (1µA typ) for ultra-low-power portable applications. It integrates column drivers (COL2–COL7/PORT2–PORT7) and supports GPO reconfiguration, key release detection, and hardware interrupt generation.

For engineers reviewing the MAX7359ETG+T datasheet, MAX7359ETG+T pinout, MAX7359ETG+T application, or MAX7359ETG+T equivalent, this device delivers deterministic key-event timing, low-EMI operation via static monitoring, I²C timeout control, user-configurable debounce (9–40ms), and seamless integration into space-constrained handheld systems requiring robust tactile input handling.

Technical Context

The MAX7359ETG+T implements a static key-scan architecture-current sources drive columns while rows are monitored for pull-down events-eliminating dynamic switching noise and enabling routing near RF/analog sections. Its internal 64kHz oscillator drives all timing, including debounce, autorepeat, and autosleep intervals.

Key event processing occurs in hardware: debounced presses/releases populate a 16-deep FIFO; interrupt logic triggers either on FIFO fill level (4–16 entries) or time-based debounce cycles (1–31); and register-controlled GPO mode allows up to seven open-drain outputs (including INT) for LED driving or system signaling.

Key Specifications

Pinout & Package

MAX7359ETG+T is housed in a 24-pin TQFN package (3.5mm × 3.5mm, exposed pad), optimized for high-density portable PCB layouts. Pin functions align with key matrix row/column topology and flexible GPO assignment.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar key switch controller applications.

Compared with MAX7359ETG+T, MAX7360ETG+ improves system integration via on-chip regulation and ESD hardening, while TCA8418RTWR trades power efficiency and FIFO depth for lower unit cost-making MAX7359ETG+T the optimal balance of ultra-low sleep current, deep event buffering, and compact packaging for premium portable devices.

Availability

MAX7359ETG+T is available at Aetrix Electronics and suitable for cell phones, PDAs, handheld games, and portable consumer electronics requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX7359ETG+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 precision analog, mixed-signal, and power management ICs for demanding industrial, automotive, and consumer applications.

The MAX7359ETG+T belongs to Maxim's human-interface peripheral product line, engineered specifically for ultra-low-power, EMI-resilient key scanning in space-constrained portable electronics.

FAQ

What is the minimum supply voltage required for reliable operation of the MAX7359ETG+T?

The MAX7359ETG+T operates reliably from +1.62V to +3.6V. At the lower limit of 1.62V, all specifications-including key-switch source current (20µA min), sleep current (0.6µA typ), and I²C timing-are guaranteed across the full −40°C to +85°C temperature range. This makes MAX7359ETG+T suitable for single-cell lithium-polymer or lithium-iron-phosphate battery systems where voltage drops below 2.0V during discharge.

Can the MAX7359ETG+T drive LEDs directly, and what is its sink current capability?

Yes, the MAX7359ETG+T can drive LEDs directly using its open-drain column/GPO pins (COL2/PORT2 through COL7/PORT7 and INT). Each pin supports up to 10mA sink current with VOL ≤ 0.2V at VCC = +2.5V and TA = +25°C. The device maintains this performance across temperature: at +85°C and VCC = +3.6V, VOL remains ≤ 0.3V at 10mA, enabling bright LED indication without external drivers.

How does the MAX7359ETG+T handle key debouncing, and is the timing adjustable?

The MAX7359ETG+T performs hardware-based key debouncing with fully user-configurable timing from 9ms to 40ms in 1ms increments, set via bits D0–D4 of the Debounce Register (0x02). This eliminates software debounce routines and ensures consistent, jitter-free key event reporting regardless of host processor load-critical for real-time UI responsiveness in handheld devices.

Does the MAX7359ETG+T support key release detection, and how is it enabled?

Yes, the MAX7359ETG+T supports optional key release detection on all 64 keys. It is enabled by setting bit D3 (Key Release Enable) to '1' in the Configuration Register (0x01). When active, the FIFO reports both press (D6 = 0) and release (D6 = 1) events for each key, allowing precise state tracking-essential for gaming controllers and accessibility interfaces requiring release-triggered actions.

What happens to the FIFO contents when the MAX7359ETG+T enters autosleep mode?

The FIFO contents are fully preserved during autosleep mode-the 16-entry buffer retains all pending key-press and key-release events. Host systems can read the FIFO at any time, even while the MAX7359ETG+T is in sleep, using standard I²C transactions. This ensures no key events are lost during low-power states, maintaining UI responsiveness without requiring wake-up synchronization.