Microchip Technology MCP23008T-E/ML

Overview

MCP23008T-E/ML from Microchip Technology is an 8-bit I²C-compatible GPIO expander IC designed to extend parallel digital I/O capability in space-constrained embedded systems. It features 8 bidirectional I/O pins (GP0–GP7), hardware address pins A2–A0 for up to eight devices on one bus, configurable interrupt output (INT), and operates from 1.8V to 5.5V across –40°C to +85°C. It is commonly used to add digital control and monitoring capability to microcontroller-based industrial sensors and smart home hubs.

For engineers reviewing the MCP23008T-E/ML datasheet, MCP23008T-E/ML pinout, MCP23008T-E/ML application, or MCP23008T-E/ML equivalent, key selection criteria include I²C interface speed (up to 1.7 MHz), low standby current (1 µA max), interrupt-on-change flexibility, and QFN-20 package compatibility with high-density PCB layouts.

Technical Context

The MCP23008T-E/ML implements a register-mapped I²C slave interface with eleven 8-bit configuration registers-including IODIR, IPOL, GPINTEN, DEFVAL, INTCON, IOCON, GPPU, INTF, INTCAP, GPIO, and OLAT-enabling precise per-pin direction, polarity, pull-up, interrupt source, and capture control. Its interrupt logic supports two mutually exclusive modes: change-from-previous-state or change-from-DEFVAL-register.

It uses a dedicated hardware address decoder (A2:A0) for 7-bit I²C addressing (base 0x20), supports sequential and byte-mode register access via the SEQOP bit in IOCON, and includes Power-on Reset (POR) with VDD rise-time tolerance (≥0.05 V/ms). The device does not support SPI-only I²C-as confirmed by pin mapping (A2 = SDA/SO on MCP23S08 but A2 = address input on MCP23008).

Key Specifications

Pinout & Package

Package: 20-pin QFN (4 mm × 4 mm, 0.5 mm pitch), wettable flank, exposed thermal pad - optimized for automated optical inspection and thermal dissipation in compact designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar GPIO expander applications.

Compared with MCP23017-E/SP and PCA9555D,118, the MCP23008T-E/ML delivers optimal balance of compact QFN-20 packaging, integrated 100 kΩ pull-ups, and deterministic INTCAP-based interrupt handling-making it ideal for space-constrained, battery-aware, and edge-triggered I/O expansion tasks.

Availability

MCP23008T-E/ML is available at Aetrix Electronics and suitable for industrial HMI, smart building sensor hubs, and IoT edge node designs requiring stable component supply, extended temperature qualification, and QFN-packaged I/O scalability.

Supply support for MCP23008T-E/ML 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 devices, and connectivity solutions, serving industrial, automotive, and consumer markets with high-reliability silicon and development tools.

The MCP23X08 product line was designed specifically for low-pin-count, low-power I/O expansion in resource-constrained embedded systems-emphasizing ease of integration, interrupt efficiency, and broad voltage interoperability.

FAQ

What is the maximum I²C clock frequency supported by the MCP23008T-E/ML?

The MCP23008T-E/ML supports I²C operation up to 1.7 MHz under 4.5V–5.5V supply and –40°C to +125°C conditions. At 1.8V–5.5V and –40°C to +85°C, it supports 100 kHz, 400 kHz, and 1.7 MHz modes. This high-speed capability allows rapid register updates and minimizes bus occupancy in time-critical applications using the MCP23008T-E/ML.

Does the MCP23008T-E/ML support SPI communication?

No, the MCP23008T-E/ML supports only I²C communication. The SPI variant is the pin-compatible but functionally distinct MCP23S08. On the MCP23008T-E/ML, pin A2 is a hardware address input-not a serial data output-and NC/CS is unconnected. Attempting SPI signaling on this device will not yield functional communication. Always verify interface type before selecting the MCP23008T-E/ML.

How does the interrupt capture register (INTCAP) improve reliability in the MCP23008T-E/ML?

The INTCAP register in the MCP23008T-E/ML latches the exact GPIO port state at the moment an interrupt occurs. This prevents race conditions where the port state changes again before the host MCU reads GPIO, ensuring deterministic edge capture. Reading INTCAP clears the interrupt condition, making it essential for robust interrupt-driven firmware using the MCP23008T-E/ML in noisy or fast-switching environments.

Can all 8 GPIO pins on the MCP23008T-E/ML be configured as outputs driving LEDs directly?

Yes-each GP0–GP7 pin on the MCP23008T-E/ML can source or sink up to 25 mA, sufficient to drive standard LEDs without external transistors. When configured as outputs, they operate from the same VDD supply (1.8V–5.5V), enabling direct connection to 3.3V or 5V LED anodes/cathodes. Always observe total package current limits (125 mA into VDD, 150 mA out of VSS) when driving multiple LEDs simultaneously with the MCP23008T-E/ML.

What is the purpose of the IOCON.SEQOP bit in the MCP23008T-E/ML?

The IOCON.SEQOP bit (bit 5 of register 0x05) controls whether the MCP23008T-E/ML's internal address pointer auto-increments after each I²C byte transfer. When cleared (SEQOP = 0), sequential reads/writes across multiple registers occur in one transaction-e.g., reading all 11 registers with a single START and STOP. When set (SEQOP = 1), the address pointer holds, enabling repeated access to a single register (e.g., polling GPIO) without re-sending the address byte-enhancing efficiency in both initialization and runtime use of the MCP23008T-E/ML.