MCP23008 datasheet(3/40 Pages) MICROCHIP

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DS21919B-page 3

MCP23008/MCP23S08

1.0

DEVICE OVERVIEW

The

MCP23X08

device

provides

8-bit,

general

purpose, parallel I/O expansion for I2C bus or SPI

applications. The two devices differ in the number of

hardware address pins and the serial interface:

• MCP23008 – I2C interface; three address pins

• MCP23S08 – SPI interface; two address pins

The MCP23X08 consists of multiple 8-bit configuration

registers for input, output and polarity selection. The

system master can enable the I/Os as either inputs or

outputs by writing the I/O configuration bits. The data

for each input or output is kept in the corresponding

Input or Output register. The polarity of the Input Port

The interrupt output can be configured to activate

under two conditions (mutually exclusive):

When

any

input

state

differs

from

its

corresponding input port register state. This is

used to indicate to the system master that an

input state has changed.

When an input state differs from a preconfigured

The Interrupt Capture register captures port values at

the time of the interrupt, thereby saving the condition

that caused the interrupt.

The Power-on Reset (POR) sets the registers to their

default values and initializes the device state machine.

The hardware address pins are used to determine the

device address.

1.1

Pin Descriptions

TABLE 1-1:

PINOUT DESCRIPTION

Name

PDIP/S

OIC

SSOP

Type

Function

SCL/SCK

Serial clock input.

SDA/SI

I/O

Serial data I/O (MCP23008)/Serial data input (MCP23S08).

A2/SO

I/O

Hardware address input (MCP23008)/Serial data output (MCP23S08).

A2 must be biased externally.

Hardware address input. Must be biased externally.

RESET

External reset input

NC/CS

No connect (MCP23008)/External chip select input (MCP23S08).

INT

Interrupt output. Can be configured for active-high, active-low or open-drain.

VSS

Ground.

GP0

I/O