MCP23008 Expander: Features, Pinout, and Datasheet
18 Termination 2.54mm 5V I/O Expander MCP23008 18 Pin 5V 18-DIP (0.300, 7.62mm)









18 Termination 2.54mm 5V I/O Expander MCP23008 18 Pin 5V 18-DIP (0.300, 7.62mm)
For I²C bus or SPI applications, the MCP23008 device provides 8-bit general-purpose parallel I/O expansion. This article mainly introduces features, pinout, datasheet and other detailed information about Microchip Technology MCP23008.

Arduino | Tutorial | MCP23008 Interfacing
MCP23008 Description
For I²C bus or SPI applications, the MCP23008 device provides 8-bit general-purpose parallel I/O expansion. The serial interface and the number of hardware address pins on the device are different:
• I²C interface MCP23008; three address pins
For input, output, and polarity selection, the MCP23008 has numerous 8-bit Configuration registers. By writing the I/O Configuration bits, the system master can activate the I/Os as either inputs or outputs. The data for each input and output is stored in the Input and Output registers, respectively. The Polarity Inversion register inverts the polarity of the Input Port register. The system master has access to all registers.
The interrupt output can be set to activate on one of two (mutually exclusive) conditions:
1. This is used to notify to the system master that an input state has changed when any input state differs from its matching Input Port register state.
2. When the state of an input differs from the value of a pre-configured register (DEFVAL register).
The Interrupt Capture register saves the situation that produced the interrupt by capturing port values at the moment of the interrupt.
The Power-on Reset (POR) restores the default values of the registers and starts the device state machine.
The device address is determined using the hardware address pins.
MCP23008 Pinout

Pinout
| Pin Number | Pin Name | Description |
| 1 | SCL | Serial clock input. |
| 2 | SDA | Serial data I/O. |
| 3 | A2 | Hardware address input. A2 must be biased externally. |
| 4 | A1 | Hardware address input. Must be biased externally. |
| 5 | A0 | Hardware address input. Must be biased externally. |
| 6 | RESET | External Reset input. Must be biased externally. |
| 7 | NC | No connect. |
| 8 | INT | Interrupt output. Can be configured for active-high, active-low or open-drain. |
| 9 | VSS | Ground. |
| 10 | GP0 | Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or internal weak pull-up resistor. |
| 11 | GP1 | Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or internal weak pull-up resistor. |
| 12 | GP2 | Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or internal weak pull-up resistor. |
| 13 | GP3 | Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or internal weak pull-up resistor. |
| 14 | GP4 | Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or internal weak pull-up resistor. |
| 15 | GP5 | Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or internal weak pull-up resistor. |
| 16 | GP6 | Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or internal weak pull-up resistor. |
| 17 | GP7 | Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or internal weak pull-up resistor. |
| 18 | VDD | Power. |
MCP23008 CAD Model

Symbol

Footprint

3D Model
MCP23008 Features
• 8-Bit Remote Bidirectional I/O Port
- I/O pins default to input
• High-Speed I2C Interface
- 100 kHz
- 400 kHz
- 1.7 MHz
• Hardware Address Pins
- Three for the MCP23008 to allow up to eight devices on the bus
- Two for the MCP23S08 to allow up to four devices using the same Chip Select
• Configurable Interrupt Output Pin
- Configurable as active-high, active-low or open-drain
• Configurable Interrupt Source
- Interrupt-on-change from configured defaults or pin change
• Polarity Inversion Register to Configure the Polarity of the Input Port Data
• External Reset Input
• Low Standby Current: 1 µA (max.)
• Operating Voltage:
- 1.8V to 5.5V at -40°C to +85°C
I²C at 100 kHz
SPI at 5 MHz
- 2.7V to 5.5V at -40°C to +85°C
I²C at 400 kHz
SPI at 10 MHz
- 4.5V to 5.5V at -40°C to +125°C
I²C at 1.7 kHz
SPI at 10 MHz
Specifications
- TypeParameter
- Factory Lead Time1 Weeks
- Mount
In electronic components, the term "Mount" typically refers to the method or process of physically attaching or fixing a component onto a circuit board or other electronic device. This can involve soldering, adhesive bonding, or other techniques to secure the component in place. The mounting process is crucial for ensuring proper electrical connections and mechanical stability within the electronic system. Different components may have specific mounting requirements based on their size, shape, and function, and manufacturers provide guidelines for proper mounting procedures to ensure optimal performance and reliability of the electronic device.
Through Hole - Mounting Type
The "Mounting Type" in electronic components refers to the method used to attach or connect a component to a circuit board or other substrate, such as through-hole, surface-mount, or panel mount.
Through Hole - Package / Case
refers to the protective housing that encases an electronic component, providing mechanical support, electrical connections, and thermal management.
18-DIP (0.300, 7.62mm) - Number of Pins18
- Number of I/Os8
- Operating Temperature
The operating temperature is the range of ambient temperature within which a power supply, or any other electrical equipment, operate in. This ranges from a minimum operating temperature, to a peak or maximum operating temperature, outside which, the power supply may fail.
-40°C~125°C - Packaging
Semiconductor package is a carrier / shell used to contain and cover one or more semiconductor components or integrated circuits. The material of the shell can be metal, plastic, glass or ceramic.
Tube - Published2003
- JESD-609 Code
The "JESD-609 Code" in electronic components refers to a standardized marking code that indicates the lead-free solder composition and finish of electronic components for compliance with environmental regulations.
e3 - Pbfree Code
The "Pbfree Code" parameter in electronic components refers to the code or marking used to indicate that the component is lead-free. Lead (Pb) is a toxic substance that has been widely used in electronic components for many years, but due to environmental concerns, there has been a shift towards lead-free alternatives. The Pbfree Code helps manufacturers and users easily identify components that do not contain lead, ensuring compliance with regulations and promoting environmentally friendly practices. It is important to pay attention to the Pbfree Code when selecting electronic components to ensure they meet the necessary requirements for lead-free applications.
yes - Part Status
Parts can have many statuses as they progress through the configuration, analysis, review, and approval stages.
Active - Moisture Sensitivity Level (MSL)
Moisture Sensitivity Level (MSL) is a standardized rating that indicates the susceptibility of electronic components, particularly semiconductors, to moisture-induced damage during storage and the soldering process, defining the allowable exposure time to ambient conditions before they require special handling or baking to prevent failures
1 (Unlimited) - Number of Terminations18
- ECCN Code
An ECCN (Export Control Classification Number) is an alphanumeric code used by the U.S. Bureau of Industry and Security to identify and categorize electronic components and other dual-use items that may require an export license based on their technical characteristics and potential for military use.
EAR99 - Terminal Finish
Terminal Finish refers to the surface treatment applied to the terminals or leads of electronic components to enhance their performance and longevity. It can improve solderability, corrosion resistance, and overall reliability of the connection in electronic assemblies. Common finishes include nickel, gold, and tin, each possessing distinct properties suitable for various applications. The choice of terminal finish can significantly impact the durability and effectiveness of electronic devices.
Matte Tin (Sn) - Voltage - Supply
Voltage - Supply refers to the range of voltage levels that an electronic component or circuit is designed to operate with. It indicates the minimum and maximum supply voltage that can be applied for the device to function properly. Providing supply voltages outside this range can lead to malfunction, damage, or reduced performance. This parameter is critical for ensuring compatibility between different components in a circuit.
1.8V~5.5V - Terminal Position
In electronic components, the term "Terminal Position" refers to the physical location of the connection points on the component where external electrical connections can be made. These connection points, known as terminals, are typically used to attach wires, leads, or other components to the main body of the electronic component. The terminal position is important for ensuring proper connectivity and functionality of the component within a circuit. It is often specified in technical datasheets or component specifications to help designers and engineers understand how to properly integrate the component into their circuit designs.
DUAL - Peak Reflow Temperature (Cel)
Peak Reflow Temperature (Cel) is a parameter that specifies the maximum temperature at which an electronic component can be exposed during the reflow soldering process. Reflow soldering is a common method used to attach electronic components to a circuit board. The Peak Reflow Temperature is crucial because it ensures that the component is not damaged or degraded during the soldering process. Exceeding the specified Peak Reflow Temperature can lead to issues such as component failure, reduced performance, or even permanent damage to the component. It is important for manufacturers and assemblers to adhere to the recommended Peak Reflow Temperature to ensure the reliability and functionality of the electronic components.
NOT SPECIFIED - Supply Voltage
Supply voltage refers to the electrical potential difference provided to an electronic component or circuit. It is crucial for the proper operation of devices, as it powers their functions and determines performance characteristics. The supply voltage must be within specified limits to ensure reliability and prevent damage to components. Different electronic devices have specific supply voltage requirements, which can vary widely depending on their design and intended application.
5V - Terminal Pitch
The center distance from one pole to the next.
2.54mm - Time@Peak Reflow Temperature-Max (s)
Time@Peak Reflow Temperature-Max (s) refers to the maximum duration that an electronic component can be exposed to the peak reflow temperature during the soldering process, which is crucial for ensuring reliable solder joint formation without damaging the component.
NOT SPECIFIED - Base Part Number
The "Base Part Number" (BPN) in electronic components serves a similar purpose to the "Base Product Number." It refers to the primary identifier for a component that captures the essential characteristics shared by a group of similar components. The BPN provides a fundamental way to reference a family or series of components without specifying all the variations and specific details.
MCP23008 - Pin Count
a count of all of the component leads (or pins)
18 - Qualification Status
An indicator of formal certification of qualifications.
Not Qualified - Output Type
The "Output Type" parameter in electronic components refers to the type of signal or data that is produced by the component as an output. This parameter specifies the nature of the output signal, such as analog or digital, and can also include details about the voltage levels, current levels, frequency, and other characteristics of the output signal. Understanding the output type of a component is crucial for ensuring compatibility with other components in a circuit or system, as well as for determining how the output signal can be utilized or processed further. In summary, the output type parameter provides essential information about the nature of the signal that is generated by the electronic component as its output.
Push-Pull - Power Supplies
an electronic circuit that converts the voltage of an alternating current (AC) into a direct current (DC) voltage.?
5V - Number of Channels1
- Interface
In electronic components, the term "Interface" refers to the point at which two different systems, devices, or components connect and interact with each other. It can involve physical connections such as ports, connectors, or cables, as well as communication protocols and standards that facilitate the exchange of data or signals between the connected entities. The interface serves as a bridge that enables seamless communication and interoperability between different parts of a system or between different systems altogether. Designing a reliable and efficient interface is crucial in ensuring proper functionality and performance of electronic components and systems.
I2C - Number of Ports
A port is identified for each transport protocol and address combination by a 16-bit unsigned number,.
1 - Nominal Supply Current
Nominal current is the same as the rated current. It is the current drawn by the motor while delivering rated mechanical output at its shaft.
1mA - Power Dissipation
the process by which an electronic or electrical device produces heat (energy loss or waste) as an undesirable derivative of its primary action.
700mW - Output Current
The rated output current is the maximum load current that a power supply can provide at a specified ambient temperature. A power supply can never provide more current that it's rated output current unless there is a fault, such as short circuit at the load.
25mA - Number of Bits8
- Clock Frequency
Clock frequency, also known as clock speed, refers to the rate at which a processor or electronic component can execute instructions. It is measured in hertz (Hz) and represents the number of cycles per second that the component can perform. A higher clock frequency typically indicates a faster processing speed and better performance. However, it is important to note that other factors such as architecture, efficiency, and workload also play a significant role in determining the overall performance of a component. In summary, clock frequency is a crucial parameter that influences the speed and efficiency of electronic components in processing data and executing tasks.
1.7MHz - Interrupt Output
In electronic components, "Interrupt Output" refers to a feature that allows a device to signal the occurrence of a specific event or condition that requires immediate attention from the system or user. When the specified event occurs, the interrupt output generates a signal to pause the normal operation of the device and divert the attention to handle the urgent task. This feature is commonly used in microcontrollers, processors, and other integrated circuits to efficiently manage tasks and prioritize critical operations. By utilizing interrupt outputs, electronic systems can respond promptly to important events, improve overall performance, and enhance real-time responsiveness.
Yes - Features
In the context of electronic components, the term "Features" typically refers to the specific characteristics or functionalities that a particular component offers. These features can vary depending on the type of component and its intended use. For example, a microcontroller may have features such as built-in memory, analog-to-digital converters, and communication interfaces like UART or SPI.When evaluating electronic components, understanding their features is crucial in determining whether they meet the requirements of a particular project or application. Engineers and designers often look at features such as operating voltage, speed, power consumption, and communication protocols to ensure compatibility and optimal performance.In summary, the "Features" parameter in electronic components describes the unique attributes and capabilities that differentiate one component from another, helping users make informed decisions when selecting components for their electronic designs.
POR - Height Seated (Max)
Height Seated (Max) is a parameter in electronic components that refers to the maximum allowable height of the component when it is properly seated or installed on a circuit board or within an enclosure. This specification is crucial for ensuring proper fit and alignment within the overall system design. Exceeding the maximum seated height can lead to mechanical interference, electrical shorts, or other issues that may impact the performance and reliability of the electronic device. Manufacturers provide this information to help designers and engineers select components that will fit within the designated space and function correctly in the intended application.
5.334mm - Width7.62mm
- REACH SVHC
The parameter "REACH SVHC" in electronic components refers to the compliance with the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulation regarding Substances of Very High Concern (SVHC). SVHCs are substances that may have serious effects on human health or the environment, and their use is regulated under REACH to ensure their safe handling and minimize their impact.Manufacturers of electronic components need to declare if their products contain any SVHCs above a certain threshold concentration and provide information on the safe use of these substances. This information allows customers to make informed decisions about the potential risks associated with using the components and take appropriate measures to mitigate any hazards.Ensuring compliance with REACH SVHC requirements is essential for electronics manufacturers to meet regulatory standards, protect human health and the environment, and maintain transparency in their supply chain. It also demonstrates a commitment to sustainability and responsible manufacturing practices in the electronics industry.
No SVHC - RoHS Status
RoHS means “Restriction of Certain Hazardous Substances” in the “Hazardous Substances Directive” in electrical and electronic equipment.
ROHS3 Compliant - Lead Free
Lead Free is a term used to describe electronic components that do not contain lead as part of their composition. Lead is a toxic material that can have harmful effects on human health and the environment, so the electronics industry has been moving towards lead-free components to reduce these risks. Lead-free components are typically made using alternative materials such as silver, copper, and tin. Manufacturers must comply with regulations such as the Restriction of Hazardous Substances (RoHS) directive to ensure that their products are lead-free and environmentally friendly.
Lead Free
Parts with Similar Specs
- ImagePart NumberManufacturerPackage / CaseNumber of PinsInterfaceSupply VoltageMountTerminal PositionPower SuppliesECCN CodeView Compare
MCP23008-E/P
18-DIP (0.300, 7.62mm)
18
I2C
5 V
Through Hole
DUAL
5 V
EAR99
16-DIP (0.300, 7.62mm)
16
RS-232
5 V
Through Hole
DUAL
5 V
EAR99
MCP23008 Functional Block Diagram

Functional Block Diagram
MCP23008 Arduino Interfacing
The project we'll talk about will show us how to connect an Arduino microcontroller to an MCP23008 I/O port expander.
First, we'll go over project components.
Component of Project
• These are the main components of the project.
• MCP23008 I/O Port Expander.
• A few 220Ω resistors.
• A few LEDs.
• Arduino microcontroller.
Let us now go over our projects in greater depth.
A 220 resistor and an LED are connected to each input and output pin in this circuit.
We wired +5V to Vdd and Vss to GND for the input supply.
Connect analog pin 5 of the Arduino to pin 1 of the MCP23008, which is SCL. This ensures that the Arduino and the I/O port expander chip are on the same clock.
After that, we connected SDA pin 2 of the MCP23008 to analog pin 4 of the Arduino. Data can be transferred between the Arduino and the I/O port expander chip using this connection.
Because the interrupts pin isn't used in this project, leave it disconnected.
The RESET pin is not used; instead, it is connected to +5V. If you wish to use it, simply attach it to the Arduino's digital pin, If you want to reset all of the outputs, set this pin to low in cade.
Following that, we'll ground address pins A0, A1, and A2. The address of these three pins becomes 000.
Let's look at the illustration for a better understanding.

Arduino Interfacing
MCP23008 Alternatives
| Part Number | Description | Manufacturer |
| MCP23S09T-E/SSMICROCONTROLLERS AND PROCESSORS | 8 I/O, PIA-GENERAL PURPOSE, PDSO20, 5.30 MM, LEAD FREE, PLASTIC, SSOP-20 | Microchip Technology Inc |
| MCP23S09-E/SOMICROCONTROLLERS AND PROCESSORS | 8 I/O, PIA-GENERAL PURPOSE, PDSO18, 7.50 MM, LEAD FREE, PLASTIC, SOIC-18 | Microchip Technology Inc |
| MCP23S08T-E/SOMICROCONTROLLERS AND PROCESSORS | 8 I/O, PIA-GENERAL PURPOSE, PDSO18, 0.300 INCH, PLASTIC, SOIC-18 | Microchip Technology Inc |
| MCP23008-E/SSVAOMICROCONTROLLERS AND PROCESSORS | Parallel I/O Port, 8 I/O, CMOS, PDSO20 | Microchip Technology Inc |
| MCP23S09-E/PMICROCONTROLLERS AND PROCESSORS | 8 I/O, PIA-GENERAL PURPOSE, PDIP18, 0.300 INCH, LEAD FREE, PLASTIC, DIP-18 | Microchip Technology Inc |
| MCP23008T-E/SSVAOMICROCONTROLLERS AND PROCESSORS | Parallel I/O Port, 8 I/O, CMOS, PDSO20 | Microchip Technology Inc |
| MCP23S08-E/SOVAOMICROCONTROLLERS AND PROCESSORS | Parallel I/O Port, 8 I/O, CMOS, PDSO18 | Microchip Technology Inc |
| MCP23009-E/SOMICROCONTROLLERS AND PROCESSORS | 8 I/O, PIA-GENERAL PURPOSE, PDSO18, 7.50 MM, LEAD FREE, PLASTIC, SOIC-18 | Microchip Technology Inc |
MCP23008 Applications
Because this microcontroller supports both the I2C and SPI protocols, it is utilized in a variety of projects and devices that employ both.
MCP23008 Package

Package
MCP23008 Manufacturer
Microchip Technology Incorporated is a leading manufacturer of smart, networked, and secure embedded control solutions. Customers may create optimal designs using the company's simple development tools and broad product choices, which reduce risk while lowering overall system costs and time to market. The company's technologies are used by over 120,000 clients in the industrial, automotive, consumer, aerospace and defense, communications, and computing sectors. Microchip Technology Inc., based in Chandler, Arizona, offers outstanding technical assistance as well as reliable delivery and quality.
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