Analog Devices Inc./Maxim Integrated MAX7359EWA+T

Overview

MAX7359EWA+T from Maxim Integrated is a 2-wire (I²C) interfaced key switch controller/GPO that manages up to 64 metallic or resistive keys with static matrix scanning, 16-entry debounced FIFO, and configurable autosleep (1µA typ) for ultra-low-power portable interfaces. It supports +1.62V to +3.6V supply, 400kbps I²C, and operates from –40°C to +85°C in a 25-bump WLP (2.31mm × 2.31mm).

For engineers reviewing the MAX7359EWA+T datasheet, MAX7359EWA+T pinout, MAX7359EWA+T application, or MAX7359EWA+T equivalent, this page delivers verified technical context on key-scan architecture, GPO reconfiguration, interrupt modes (FIFO- or time-based), sleep/wake behavior, and WLP package-specific layout considerations.

Technical Context

The MAX7359EWA+T implements static key-matrix monitoring-no dynamic row/column toggling-to minimize EMI and enable routing near noise-sensitive analog sections. Its internal 64kHz oscillator drives key-scan timing, and all key events (press/release, autorepeat) are debounced and queued in a 16-byte FIFO with user-configurable 9ms–40ms debounce windows.

Autosleep triggers after programmable idle time (up to 8192ms); autowake resumes full operation within 2ms of key press while preserving FIFO contents. Up to seven open-drain outputs (COL2/PORT2–COL7/PORT7 and INT) can be repurposed as GPOs-each GPO conversion reduces scan capacity by eight keys.

Key Specifications

Pinout & Package

MAX7359EWA+T uses a 25-bump Wafer-Level Package (WLP), 2.31mm × 2.31mm, 0.4mm pitch, RoHS-compliant. The package has no exposed pad and requires microvia routing for bottom-side connections.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX7359EWA+T, MAX7360EWA+T offers lower integration for cost-sensitive 32-key systems, while TCA8418RTWR provides comparable low-power performance but sacrifices GPO configurability and key scalability-making MAX7359EWA+T optimal for compact, high-flexibility keypad subsystems.

Availability

MAX7359EWA+T is available at Aetrix Electronics and suitable for smartphone keypad interfaces, industrial handheld terminals, portable medical device UIs, gaming handheld control panels, and ruggedized PDA applications requiring stable component supply and long-term lifecycle support.

Supply support for MAX7359EWA+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 MAX7359EWA+T belongs to Maxim's key-switch controller product line, engineered specifically for ultra-low-power, EMI-conscious human interface subsystems in space-constrained portable electronics.

FAQ

What is the maximum number of keys supported by the MAX7359EWA+T?

The MAX7359EWA+T supports up to 64 keys in an 8×8 matrix configuration. Each key is scanned using static monitoring, and all press/release events are debounced and stored in a 16-entry FIFO. When configured with GPO functionality, the key count decreases by eight keys per enabled GPO port (e.g., enabling two GPOs reduces capacity to 48 keys). This scalability is implemented in hardware and requires no firmware changes.

How does the autosleep and autowake functionality operate in the MAX7359EWA+T?

The MAX7359EWA+T enters autosleep mode after a programmable idle period (configurable from 256ms to 8192ms via register 0x06), reducing supply current to 0.6µA–5µA. A key press triggers autowake, restoring full operation within 2ms while preserving FIFO contents. Autosleep and autowake can be individually disabled via bits D7 and D1 in the Configuration Register (0x01). The device does not enter autosleep during key-hold conditions.

Can the INT pin on the MAX7359EWA+T be used as a general-purpose output?

Yes-the INT pin on the MAX7359EWA+T is configurable as an open-drain general-purpose output (GPO) when interrupt functionality is disabled. This is controlled via the Interrupt Register (0x03): writing 0x00 to this register disables INT and enables GPO control through bit D1 of the Ports Register (0x04). As a GPO, INT supports up to 25mA sink current and can drive LEDs or logic-level signals directly.

What are the I²C voltage tolerance and timing specifications for the MAX7359EWA+T?

The MAX7359EWA+T features 5.5V-tolerant SDA and SCL inputs, supporting mixed-voltage systems where the host MCU runs at 5V while the MAX7359EWA+T operates from 1.62V–3.6V. It complies with standard-mode and fast-mode I²C (up to 400kbps), with guaranteed timing parameters including tSU,DAT ≥100ns, tHD,DAT ≥0.9µs, and tLOW/tHIGH ≥1.3µs/0.7µs. Bus timeout is configurable from 10ms to 40ms to prevent lockup.

Does the MAX7359EWA+T support key release detection and autorepeat?

Yes-the MAX7359EWA+T supports optional key release detection on all 64 keys, enabled via bit D3 in the Configuration Register (0x01). Autorepeat is fully configurable: delay (8–128 debounce cycles) and frequency (4–32 cycles) are set in the Autorepeat Register (0x05). When active, holding a key generates repeated 0x7E codes in the FIFO-distinct from the original key code-and continues until release or another key event occurs.