Datasheet

© 2007 Microchip Technology Inc. DS21919E-page 5
MCP23008/MCP23S08
1.0 DEVICE OVERVIEW
The MCP23X08 device provides 8-bit, general
purpose, parallel I/O expansion for I
2
C bus or SPI
applications. The two devices differ in the number of
hardware address pins and the serial interface:
• MCP23008 – I
2
C 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
register can be inverted with the Polarity Inversion
register. All registers can be read by the system master.
The interrupt output can be configured to activate
under two conditions (mutually exclusive):
1. 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.
2. When an input state differs from a preconfigured
register value (DEFVAL register).
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
Pin
Name
PDIP/
SOIC
QFN SSOP
Pin
Type
Function
SCL/SCK 1 19 1 I Serial clock input.
SDA/SI 2 20 2 I/O Serial data I/O (MCP23008)/Serial data input (MCP23S08).
A2/SO 3 1 3 I/O Hardware address input (MCP23008)/
Serial data output (MCP23S08).
A2 must be biased externally.
A1 4 2 4 I Hardware address input. Must be biased externally.
A0 5 3 5 I Hardware address input. Must be biased externally.
RESET
6 4 6 I External reset input. Must be biased externally.
NC/CS
7 5 7 I No connect (MCP23008)/External chip select input (MCP23S08).
INT 8 7 8 O Interrupt output. Can be configured for active-high, active-low or
open-drain.
V
SS 9179PGround.
GP0 10 9 12 I/O Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or
internal weak pull-up resistor.
GP1 11 10 13 I/O Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or
internal weak pull-up resistor.
GP2 12 11 14 I/O Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or
internal weak pull-up resistor.
GP3 13 12 15 I/O Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or
internal weak pull-up resistor.
GP4 14 13 16 I/O Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or
internal weak pull-up resistor.
GP5 15 14 17 I/O Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or
internal weak pull-up resistor.
GP6 16 15 18 I/O Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or
internal weak pull-up resistor.
GP7 17 16 19 I/O Bidirectional I/O pin. Can be enabled for interrupt-on-change and/or
internal weak pull-up resistor.
V
DD 18 18 20 P Power.
N/C — 6, 8 10, 11 — —