Microchip Technology MCP23008-E/SO

Overview

MCP23008-E/SO from Microchip Technology is an 8-bit I²C-compatible I/O expander IC designed to extend microcontroller GPIO capability in space-constrained systems. It features 8 bidirectional I/O pins (GP0–GP7), hardware address pins A2–A0 for up to eight devices on one bus, configurable active-high/low/open-drain interrupt output (INT), and operates from 1.8V to 5.5V across –40°C to +85°C. It is commonly used in industrial HMI panels to offload button/LED control from main MCUs.

For engineers reviewing the MCP23008-E/SO datasheet, MCP23008-E/SO pinout, MCP23008-E/SO application, or MCP23008-E/SO equivalent, key selection considerations include its I²C interface speed (up to 1.7 MHz), low standby current (1 µA max), interrupt-on-change flexibility, and SOIC-18 package compatibility with standard PCB footprints.

Technical Context

The MCP23008-E/SO implements a register-mapped I²C slave interface with eleven 8-bit configuration registers-including IODIR for direction control, IPOL for input polarity inversion, GPINTEN/INTCON/DEFVAL for dual-mode interrupt triggering (pin-change or default-compare), and GPPU for per-pin 100 kΩ weak pull-ups. Its internal Power-on Reset (POR) initializes all registers to defined defaults without external reset circuitry.

Interrupt logic captures port state into INTCAP at event time and asserts INT only when enabled pins transition relative to either prior state or DEFVAL register contents. The IOCON register configures sequential addressing, SDA slew rate, and INT pin behavior (push-pull polarity or open-drain mode), with no HAEN bit support-confirming it is strictly the I²C variant (MCP23008), not SPI (MCP23S08).

Key Specifications

Pinout & Package

Package: 18-pin SOIC (300 mil), RoHS-compliant, surface-mountable with standard 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9554APW,118 and TCA6408APWR, the MCP23008-E/SO provides superior interrupt diagnostics via INTCAP, flexible multi-device addressing via A2–A0, and richer configuration (e.g., dual interrupt modes, per-pin pull-ups), making it preferred for complex, scalable industrial control designs.

Availability

MCP23008-E/SO is available at Aetrix Electronics and suitable for industrial HMI panels, smart sensor nodes, automated test equipment, and IoT gateway control boards requiring stable component supply and long-term manufacturability.

Supply support for MCP23008-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 components, and connectivity solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The MCP23X08 product line delivers scalable, register-configurable I/O expansion for resource-constrained embedded systems-designed specifically to reduce GPIO pressure in industrial, automotive, and consumer control applications.

FAQ

What communication interface does the MCP23008-E/SO support?

The MCP23008-E/SO supports only the I²C interface-not SPI. It uses SCL and SDA pins for bidirectional serial communication, with hardware address pins A2–A0 enabling up to eight devices on one I²C bus. Its datasheet explicitly distinguishes it from the SPI-based MCP23S08 variant, and the pinout confirms absence of SI/SO/CS pins. The MCP23008-E/SO operates at I²C speeds up to 1.7 MHz under 4.5V–5.5V conditions.

Does the MCP23008-E/SO include internal pull-up resistors on its GPIO pins?

Yes, the MCP23008-E/SO includes software-controllable 100 kΩ internal weak pull-up resistors on all eight GPIO pins (GP0–GP7). These are enabled individually via the GPPU register bits. When a pin is configured as an input (IODIR bit = 1), setting the corresponding PUx bit activates the pull-up. This eliminates the need for external resistors in many switch-sensing applications, directly reducing BOM cost and PCB area. The MCP23008-E/SO does not provide pull-downs.

How does the interrupt functionality work on the MCP23008-E/SO?

The MCP23008-E/SO supports two interrupt modes: interrupt-on-change from previous state or from a user-defined DEFVAL register. Interrupts are enabled per-pin via GPINTEN and configured via INTCON. When triggered, the port state is captured in INTCAP, and INT asserts until INTCAP or GPIO is read. The INT pin is configurable as active-high, active-low, or open-drain using IOCON. This makes the MCP23008-E/SO highly adaptable for reliable edge detection in noisy environments.

What is the operating voltage range and temperature grade of the MCP23008-E/SO?

The MCP23008-E/SO operates from 1.8V to 5.5V across the industrial temperature range of –40°C to +85°C. At 4.5V–5.5V, it also supports extended operation up to +125°C (E-temp grade), with maximum standby current specified at 2 µA under those conditions. Its wide VDD range allows seamless interoperability with 1.8V logic families and legacy 5V systems without level shifters-making the MCP23008-E/SO suitable for mixed-voltage embedded designs.

Can the MCP23008-E/SO be used in place of the MCP23S08?

No, the MCP23008-E/SO cannot be used as a drop-in replacement for the MCP23S08 because they use fundamentally different serial interfaces-I²C versus SPI-and have incompatible pinouts. The MCP23008-E/SO has A2, SDA, and SCL pins; the MCP23S08 has SI, SO, SCK, and CS. Their address pin counts differ (three vs. two), and register-level behavior varies (e.g., IOCON.HAEN is unused in MCP23008-E/SO). Firmware, schematic, and layout changes would be required to substitute one for the other.