Microchip Technology MCP23S18T-E/MJVAO

Overview

MCP23S18T-E/MJVAO from Microchip Technology is a 16-bit SPI-based I/O expander with open-drain outputs, 5.5V-tolerant inputs, 25 mA sink capability per pin, and automotive AEC-Q100 qualification. It serves as a remote parallel I/O extension for microcontrollers in space-constrained industrial control panels requiring high-pin-count GPIO expansion without I²C bus contention.

For engineers reviewing the MCP23S18T-E/MJVAO datasheet, MCP23S18T-E/MJVAO pinout, MCP23S18T-E/MJVAO application, or MCP23S18T-E/MJVAO equivalent, key selection criteria include SPI interface speed (10 MHz), interrupt configuration flexibility (INTA/INTB active-high/low/open-drain), 1.8–5.5V operating range, and QFN-24 package thermal performance.

Technical Context

The MCP23S18T-E/MJVAO implements two independent 8-bit bidirectional ports (PORTA and PORTB) with configurable direction, polarity inversion, and interrupt-on-change logic. Its SPI interface supports full-duplex communication at up to 10 MHz across 1.8–5.5V VDD, with hardware reset and chip-select control enabling robust multi-device daisy-chaining.

Interrupt generation is configurable per port via INTCON registers to trigger on input state change versus DEFVAL register mismatch, and captured port states are stored in INTCAP registers. The IOCON.BANK bit selects between byte-aligned (BANK=0) or port-segregated (BANK=1) register addressing modes for flexible firmware access.

Key Specifications

Pinout & Package

Package: 24-pin QFN (4×4 mm, 0.5 mm pitch) with exposed thermal pad (EP) - optimized for compact PCB layouts and thermal dissipation in enclosed enclosures.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I/O expander applications.

Compared with MCP23018T-E/MJVAO and TCA6424ARGJR, the MCP23S18T-E/MJVAO uniquely delivers SPI-native 16-bit expansion with AEC-Q100 compliance and dual interrupt outputs-critical for deterministic timing and automotive safety-critical subsystems.

Availability

MCP23S18T-E/MJVAO is available at Aetrix Electronics and suitable for industrial HMI panels, automotive body control modules, and smart energy meter interfaces requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.

Supply support for MCP23S18T-E/MJVAO 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

Microchip Technology Inc. is a leading provider of microcontroller, mixed-signal, analog, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets.

The MCP23X18 product line delivers scalable, low-power I/O expansion for resource-constrained embedded systems, with variants optimized for SPI (MCP23S18) or I²C (MCP23018) host interfaces and automotive-grade reliability.

FAQ

What interface protocol does the MCP23S18T-E/MJVAO support?

The MCP23S18T-E/MJVAO supports only the SPI interface-not I²C. It requires four dedicated signals: CS, SCK, SI, and SO. This distinguishes it from the pin-compatible MCP23018T-E/MJVAO, which uses I²C (SCL/SDA). The SPI interface enables higher-speed communication (up to 10 MHz) and avoids I²C bus arbitration issues in multi-master systems. The MCP23S18T-E/MJVAO retains identical register mapping and functional behavior otherwise.

Does the MCP23S18T-E/MJVAO have automotive qualification?

Yes, the MCP23S18T-E/MJVAO is qualified to AEC-Q100 Grade 1 (–40°C to +125°C ambient), making it suitable for automotive body electronics, infotainment, and ADAS subsystems. This qualification covers stress testing for temperature cycling, humidity, ESD, and mechanical shock. The device's 5.5V-tolerant inputs and 25 mA sink capability per pin further support robust operation in noisy automotive environments. MCP23S18T-E/MJVAO meets these requirements across its full specified voltage range (1.8V–5.5V).

How are the interrupt outputs INTA and INTB configured on the MCP23S18T-E/MJVAO?

INTA and INTB on the MCP23S18T-E/MJVAO are independently configurable via the IOCON register's INTPOL and ODR bits. Each can be set as active-high, active-low, or open-drain. When IOCON.MIRROR = 1, both outputs reflect the logical OR of PORTA and PORTB interrupts-enabling single-wire wake-up signaling. The interrupt condition itself is defined per port using INTCON registers to trigger either on input change or deviation from DEFVAL register contents. This flexibility allows precise event handling without host polling.

What is the function of the RESET pin on the MCP23S18T-E/MJVAO?

The RESET pin on the MCP23S18T-E/MJVAO is an asynchronous, active-low hardware reset input. When asserted, it forces all internal registers-including I/O direction, polarity, pull-up, and interrupt configuration-to their power-on reset (POR) default states. Unlike software resets, this guarantees deterministic initialization regardless of SPI bus state or clock glitches. The pin must be externally pulled high (typically with a 10 kΩ resistor) and driven low only during intentional reset sequences. It is not internally debounced, so clean signal edges are required for reliable operation.

Can the MCP23S18T-E/MJVAO drive LEDs directly?

Yes, the MCP23S18T-E/MJVAO can drive LEDs directly using its open-drain outputs. Each pin supports 25 mA sink current (with 400 mA total across all 16 pins), sufficient for standard indicator LEDs without external current-limiting transistors. A series resistor (e.g., 220 Ω for 5V VDD) is still required to limit current and protect the output stage. The device's 5.5V-tolerant inputs also allow direct connection to 5V LED anodes in common-anode configurations, while the open-drain structure simplifies wiring and enables wired-OR logic for shared interrupt lines.