Microchip Technology MCP23S17-E/SP

Overview

MCP23S17-E/SP from Microchip Technology is a 16-bit remote bidirectional I/O expander with high-speed SPI interface, operating from 1.8V to 5.5V across –40°C to +85°C. It features dual 8-bit ports (PORTA and PORTB), configurable interrupt outputs (INTA/INTB), hardware address pins (A0–A2) for up to eight devices on one bus, and low standby current of 1 µA (max). It is used in industrial PLC I/O modules to extend microcontroller GPIO capability without increasing MCU pin count.

For engineers reviewing the MCP23S17-E/SP datasheet, MCP23S17-E/SP pinout, MCP23S17-E/SP application, or MCP23S17-E/SP equivalent, key selection criteria include SPI clock support up to 10 MHz, interrupt-on-change configuration per pin, internal weak pull-up resistors (40–115 µA at 5V), 28-pin SOIC package compatibility, and AEC-Q100 qualification for automotive-adjacent reliability.

Technical Context

The MCP23S17-E/SP implements a register-mapped SPI peripheral with 22 addressable control registers, supporting both byte-mode and sequential-mode transfers. Its GPIO architecture separates input state (GPIOx), output latch (OLATx), and direction control (IODIRx), enabling robust read-modify-write operations without unintended toggling.

Interrupt logic supports two independent sources per port-interrupt-on-change from default register values or from pin-level transitions-with glitch filtering (150 ns) and capture registers (INTCAPx) to preserve triggering conditions. The IOCON register configures banked vs. linear register addressing, interrupt mirroring, and open-drain output mode.

Key Specifications

Pinout & Package

The MCP23S17-E/SP is supplied in a 28-pin SOIC (Wide, 7.50 mm body) package with exposed thermal pad (EP) connected to VSS or left floating per design requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP23017-E/SP and TCA9535PWR, the MCP23S17-E/SP delivers higher-speed serial communication (10 MHz SPI vs. 1.7 MHz I²C vs. 400 kHz I²C), full interrupt configurability per port, and stronger output drive - making it optimal for deterministic, high-throughput embedded control where timing predictability and signal integrity are critical.

Availability

MCP23S17-E/SP is available at Aetrix Electronics and suitable for industrial automation, automotive subsystems, and medical device manufacturing requiring stable component supply and long-term production continuity.

Supply support for MCP23S17-E/SP 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 microcontrollers, analog, FPGA, and connectivity solutions, serving industrial, automotive, communications, and consumer markets.

The MCP23X17 product line delivers scalable, register-compatible I/O expansion for resource-constrained embedded systems - designed specifically to reduce MCU GPIO pressure while maintaining configurability, reliability, and ease of integration.

FAQ

What is the maximum SPI clock frequency supported by the MCP23S17-E/SP?

The MCP23S17-E/SP supports up to 10 MHz SPI clock frequency when VDD is ≥ 2.7V. At 1.8V operation, the maximum clock rate is 5 MHz. These limits are defined in the AC characteristics table and ensure reliable setup/hold timing for SI, SO, and SCK signals across temperature and voltage ranges.

Does the MCP23S17-E/SP support interrupt-on-change for individual pins?

Yes, the MCP23S17-E/SP supports per-pin interrupt-on-change via GPINTENA and GPINTENB registers. Each of the 16 I/O pins can be individually enabled to trigger INTA or INTB based on input state transitions, with optional 150 ns glitch filtering to reject noise.

Can the MCP23S17-E/SP operate from a 1.8V supply?

Yes, the MCP23S17-E/SP operates from 1.8V to 5.5V over –40°C to +85°C. At 1.8V, it maintains full functionality including SPI communication (up to 5 MHz), GPIO operation, and interrupt generation, with adjusted VOL/VOH thresholds specified in the DC characteristics table.

How many MCP23S17-E/SP devices can share the same SPI bus?

Up to eight MCP23S17-E/SP devices can share one SPI bus using the A0, A1, and A2 hardware address pins. Each unique 3-bit combination sets a distinct device address, allowing independent selection via the CS line without software address arbitration.

Is the MCP23S17-E/SP pin-compatible with the MCP23017-E/SP?

No, the MCP23S17-E/SP is not pin-compatible with the MCP23017-E/SP. While both share the same 28-pin SOIC package footprint and most signal names, the SPI variant uses CS, SI, SO, and SCK pins, whereas the I²C variant uses NC, SDA, SCL, and NC - requiring PCB layout changes for substitution.