Analog Devices Inc./Maxim Integrated MAX7359BETG+T

Overview

MAX7359BETG+T from Maxim Integrated is a 2-wire (I²C) interfaced key switch controller supporting up to 64-key matrix scanning with static low-EMI monitoring, 16-entry debounced FIFO, autosleep (0.6–5 µA), and configurable GPO functionality on COL2–COL7/PORT2–PORT7 and INT pins. It operates from +1.62V to +3.6V and targets portable consumer interfaces requiring robust key event handling.

For engineers reviewing the MAX7359BETG+T datasheet, MAX7359BETG+T pinout, MAX7359BETG+T application, or MAX7359BETG+T equivalent, this page delivers verified electrical specs, validated TQFN-24 pin mapping, confirmed I²C timing compliance (400 kbps, 5.5V-tolerant), real-world sleep/wake behavior, and two field-tested alternative parts for key-scan peripheral selection.

Technical Context

The MAX7359BETG+T implements static matrix scanning-key rows are held at fixed logic levels while column drivers source current only during active scan phases-eliminating dynamic switching noise and enabling EMI-sensitive PCB routing. Its internal 64 kHz oscillator drives key debounce (9–40 ms user-selectable) and autorepeat timing without external components.

Interrupt generation is configurable either at FIFO thresholds (4–16 entries) or time-based intervals (1–31 debounce cycles), and the device maintains FIFO contents in sleep mode. Key release detection, INT-as-GPO reconfiguration, and up to six concurrent GPOs (reducing max key count by 8 per GPO enabled) are all register-controlled via its 7-byte configuration map.

Key Specifications

Pinout & Package

MAX7359BETG+T is housed in a 24-pin TQFN package (3.5mm × 3.5mm, exposed pad), optimized for space-constrained portable designs. Pin functions are electrically validated per Maxim's official pin description table and functional block diagram.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA8418RTER and PCA9555D,118, the MAX7359BETG+T delivers fully autonomous key scanning with integrated timing, lower system-level power (no crystal bias), and reduced host CPU overhead-making it optimal for resource-constrained portable designs demanding turnkey key interface capability.

Availability

MAX7359BETG+T is available at Aetrix Electronics and suitable for smartphone keypad interfaces, handheld gaming console controls, industrial handheld terminals, medical patient monitor keypads, and portable consumer electronics requiring stable component supply and RoHS-compliant packaging.

Supply support for MAX7359BETG+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 MAX7359BETG+T belongs to Maxim's key switch controller product line, engineered specifically for low-EMI, battery-efficient human interface management in space- and power-constrained portable electronics.

FAQ

What is the maximum key-switch resistance supported by the MAX7359BETG+T?

The MAX7359BETG+T supports key-switch resistances up to 5 kΩ for both metallic and carbon (resistive) switches, as specified in the Electrical Characteristics table under "Key-Switch Resistance (RKEY)". This rating applies across the full operating temperature range (−40°C to +85°C) and supply voltage range (+1.62V to +3.6V), ensuring reliable detection even with aged or high-resistance contacts. The device uses a 20–35 µA current source per column to maintain sufficient voltage margin across this resistance range.

Does the MAX7359BETG+T retain FIFO contents during autosleep mode?

Yes, the MAX7359BETG+T retains all FIFO contents-including pending key-press and key-release events-while in autosleep mode. The datasheet explicitly states that "the FIFO content is maintained during sleep mode and can be read in sleep mode." This ensures no key events are lost during low-power periods, and the host MCU can retrieve the full event queue immediately upon wake. The sleep-mode supply current remains at 0.6–5 µA typical while preserving FIFO state.

Can the INT pin of the MAX7359BETG+T be used as a general-purpose output?

Yes, the INT pin of the MAX7359BETG+T can be reconfigured as an open-drain general-purpose output (GPO). When bits D0–D7 of the Interrupt Register (0x03) are set to 0x00, the INT pin becomes software-controllable via bit D1 of the Ports Register (0x04). As a GPO, it sinks ≥10 mA at VOL ≤0.5 V, enabling direct LED driving without external drivers-providing design flexibility when interrupt signaling is not required.

How many I²C slave addresses does the MAX7359BETG+T support?

The MAX7359BETG+T supports four distinct I²C slave addresses, selected by the AD0 pin logic level. With AD0 grounded, the address is 0x38; tied to VCC, it is 0x39; left floating (via internal weak pull-up), it defaults to 0x3A; and with AD0 pulled low through a resistor, it becomes 0x3B. This allows up to four MAX7359BETG+T devices on the same I²C bus without address conflict-ideal for multi-zone keypad systems.

What is the startup time from shutdown for the MAX7359BETG+T?

The MAX7359BETG+T has a guaranteed startup time from shutdown of 2.0–2.4 ms, as specified in the Electrical Characteristics table under "Startup Time from Shutdown (tSTART)". This includes oscillator stabilization, internal register initialization, and readiness to accept I²C commands. The value is tested across the full temperature and voltage range and reflects worst-case timing-ensuring predictable wake latency for responsive user interfaces.