Analog Devices Inc./Maxim Integrated MAX7348AEP+

Overview

MAX7348AEP+ from Maxim Integrated is a 2-wire (I²C) interfaced key-switch and sounder controller IC designed for low-EMI static matrix scanning of up to 40 metallic or resistive switches (≤1kΩ), with integrated 8-deep FIFO debouncing, user-configurable 9ms–40ms debounce time, and programmable tone generation (14 musical frequencies, 523Hz–2637Hz) for key-click or alarm feedback. It operates from 2.4V to 3.6V across –40°C to +125°C and delivers ≤10µA shutdown current.

For engineers reviewing the MAX7348AEP+ datasheet, MAX7348AEP+ pinout, MAX7348AEP+ application, or MAX7348AEP+ equivalent, this device serves as a drop-in-ready solution for medical instrument front panels, industrial HMI keypads, security access keypads, and instrumentation control interfaces requiring simultaneous switch monitoring and audible feedback without microprocessor polling overhead.

Technical Context

The MAX7348AEP+ implements static (non-scanned) key matrix monitoring to eliminate switching noise and EMI-each row/column transition occurs only on actual switch actuation. Its dual-function I²C interface uses two distinct 7-bit slave addresses: one for the key-scan controller (configurable via AD0 pin across four combinations) and another for the independent sounder controller, enabling concurrent register access without bus contention.

Internally, it integrates a dedicated tone generator with double-buffered command queueing, supporting seamless autoloop between two tones and programmable duration (15.625ms–1s in binary steps). The INT output supports configurable interrupt modes-including per-event, FIFO-level threshold, or periodic timeout-and can be repurposed as an open-drain GPO capable of driving LEDs.

Key Specifications

Pinout & Package

MAX7348AEP+ is housed in a 20-pin QSOP package (package code E20-1) with exposed paddle (not electrically connected), optimized for thermal performance and board space efficiency in compact industrial and medical enclosures.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar key-switch and audio feedback applications.

Compared with MAX7348AEP+, MAX7349AEG+ offers greater key capacity and enhanced alert functionality but demands PCB layout changes, while TCA9554PWR reduces integration but shifts design complexity to firmware and external components-making MAX7348AEP+ optimal for balanced integration, EMI control, and audible feedback in 40-key systems.

Availability

MAX7348AEP+ is available at Aetrix Electronics and suitable for medical instrument front panels, industrial HMI control panels, and security access keypads requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX7348AEP+ 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, medical, and automotive applications.

The MAX7347/MAX7348/MAX7349 family was engineered specifically for EMI-sensitive human-interface applications requiring reliable key detection and integrated audio feedback-eliminating external debounce circuits and sound generators.

FAQ

What is the maximum number of keys supported by the MAX7348AEP+?

The MAX7348AEP+ supports up to 40 key switches arranged in an 8-row × 5-column static matrix. This is fixed per device variant-unlike the MAX7349AEG+ (64 keys) or MAX7347AEE+ (24 keys). No firmware or configuration changes increase this limit; exceeding 40 keys requires hardware redesign or device substitution.

Can the INT pin on the MAX7348AEP+ be used as a general-purpose output?

Yes, the INT pin on the MAX7348AEP+ can be reconfigured in software as an open-drain general-purpose output (GPO) capable of sinking up to 10mA. This is controlled via the Configuration register (address 0x04) and allows driving LEDs or other low-current loads without adding external drivers-retaining full interrupt functionality when needed.

Does the MAX7348AEP+ require external components for I²C communication?

Yes, the MAX7348AEP+ requires external 4.7kΩ pullup resistors on both SDA and SCL lines to V+. It also mandates a minimum 0.047µF ceramic capacitor between V+ and GND for stable power supply decoupling. No external crystal, oscillator, or audio amplifier is needed-the tone generator and push-pull SOUNDER output are fully integrated.

What is the operating temperature range for the MAX7348AEP+?

The MAX7348AEP+ is specified for continuous operation from –40°C to +125°C. This wide industrial temperature range is validated across all electrical parameters-including key debounce timing, sounder frequency accuracy (±1.2%), and supply current-and applies to the lead-free 20-pin QSOP package (E20-1).

How does the MAX7348AEP+ achieve low-EMI key scanning?

The MAX7348AEP+ achieves low-EMI operation by using static (non-scanned) matrix monitoring-row and column lines remain quiescent until a switch closure causes a state change. Unlike multiplexed scanners that generate periodic clock harmonics, this architecture emits no scanning energy, allowing direct routing near sensitive analog or RF circuits without shielding or filtering.