Microchip Technology MCP23008T-E/SO

Overview

MCP23008T-E/SO from Microchip Technology is an 8-bit I²C-compatible I/O expander IC used to extend microcontroller GPIO resources 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 deployed in industrial HMI panels to manage LED indicators and pushbutton inputs via a single I²C interface.

For engineers reviewing the MCP23008T-E/SO datasheet, MCP23008T-E/SO pinout, MCP23008T-E/SO application, or MCP23008T-E/SO equivalent, key selection considerations include its I²C-only interface (no SPI), 18-pin SOIC package with exposed pad compatibility, interrupt-on-change capability per pin, internal weak pull-up resistors (100 kΩ), and support for 100 kHz / 400 kHz / 1.7 MHz I²C clock rates depending on VDD and temperature grade.

Technical Context

The MCP23008T-E/SO implements a register-mapped I²C slave interface with eleven 8-bit control and status registers (e.g., IODIR, GPIO, INTF, INTCAP) accessible over a 7-bit address space determined by A2–A0. Its interrupt logic supports two modes: change-detection against previous state or comparison against DEFVAL register values, with capture of port state into INTCAP at interrupt assertion.

Each GPx pin is individually configurable as input or output via the IODIR register; input polarity is invertible per pin using IPOL; internal 100 kΩ pull-ups are enabled per pin via GPPU; and the INT output is software-configurable as active-high, active-low, or open-drain via IOCON bits ODR and INTPOL.

Key Specifications

Pinout & Package

Package: 18-pin SOIC (300 mil), body width 7.5 mm, lead pitch 1.27 mm, compliant with JEDEC MS-012AC. The 'T' suffix denotes tape-and-reel packaging; 'E/SO' confirms SOIC-18 with extended temperature range (–40°C to +85°C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCF8574AT and MCP23017-E/SO, the MCP23008T-E/SO uniquely balances minimal pin count (18-pin SOIC), per-pin interrupt flexibility, and low-power operation - making it optimal for compact, interrupt-driven 8-bit expansion where cost and board area are constrained but feature richness matters.

Availability

MCP23008T-E/SO is available at Aetrix Electronics and suitable for industrial HMI panels, IoT sensor nodes, automotive body controllers, and medical device UI interfaces requiring stable component supply, long-term manufacturability, and RoHS-compliant sourcing.

Supply support for MCP23008T-E/SO 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, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The MCP23X08 family was designed specifically for cost-sensitive, space-constrained embedded systems needing reliable I²C/SPI-based GPIO expansion with robust interrupt handling and wide-voltage operation.

FAQ

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

The MCP23008T-E/SO supports I²C clock frequencies up to 1.7 MHz when operating at VDD = 4.5–5.5V and TA = –40°C to +85°C. At 1.8–2.6V, the maximum is 100 kHz; at 2.7–5.5V, it is 400 kHz. These limits are defined in the Electrical Characteristics table of DS20001919F and apply directly to the MCP23008T-E/SO variant.

Does the MCP23008T-E/SO have internal pull-up resistors on its GPIO pins?

Yes, the MCP23008T-E/SO includes programmable internal weak pull-up resistors (approximately 100 kΩ) on all eight GPx pins. These are enabled or disabled individually via bits PU0–PU7 in the GPPU register (address 0x06), and only affect pins configured as inputs via the IODIR register.

How is the I²C slave address configured for the MCP23008T-E/SO?

The MCP23008T-E/SO uses three hardware address pins - A2, A1, and A0 - to configure its 7-bit I²C slave address. With A2:A1:A0 tied to VDD or VSS, the base address 0x20 is offset to yield addresses from 0x20 to 0x27. This allows up to eight devices on the same I²C bus without software address reconfiguration.

Can the INT pin of the MCP23008T-E/SO be used as an open-drain output?

Yes, the INT pin of the MCP23008T-E/SO can be configured as an open-drain output by setting the ODR bit (bit 2) in the IOCON register (0x05). When ODR = 1, the INT pin operates as open-drain regardless of the INTPOL bit setting, enabling wired-AND interrupt sharing across multiple devices.

What happens to the MCP23008T-E/SO registers after an external RESET signal is asserted?

When the RESET pin of the MCP23008T-E/SO is pulled low, all internal registers revert to their Power-on Reset (POR) default values: IODIR = 0xFF (all inputs), GPIO = 0x00, GPPU = 0x00 (pull-ups disabled), and INT is deasserted. This ensures deterministic initialization independent of I²C bus state or prior register writes.