Flat-Panel TVs and Displays
LCD TVs, Multifunction Monitors and Plasma-Display TVs
8-Bit Bidirectional I
2
C-Bus I/O Expanders
PCF8574, PCF8574A
Get samples, datasheets and app reports at:
or
31
16-Bit Bidirectional I
2
C-Bus I/O Expanders
PCF8575, PCF8575C
Get samples, datasheets and app reports at:
or
The PCF8574 and PCF8574A provide general-purpose remote I/O expan-
sion for most microcontroller families via the I
2
C interface serial clock
(SCL) and serial data (SDA). These 8-bit input/output (I/O) expanders
for the two-line bidirectional bus (I
2
C) are designed for 2.5-V to 6-V V
CC
operation.
Key Features
• Two-wire I
2
C-bus to 8-bit bidirectional parallel-bus expander
• Addressed by three hardware-address pins
• Different I
2
C addresses for PCF8574 and PCF8574A:
•
PCF8574: 0x20 – 0x27 (up to 8 per I
2
C bus)
•
PCF8574A: 0x38 – 0x3F (up to 8 per I
2
C bus)
• A total of 16 PCF8574 and PCF8574A devices may be used on same
I
2
C bus
Applications
• Fan control
• LED control
• System monitoring
• Temperature sensor monitoring
• Push-button monitoring
• 8-bit bidirectional expansion
Temperature Sensor
Battery Status
V
CC
V
CC
Reset Signals
Status
P0
P1
P2
P3
P4
P5
P6
P7
5V
The PCF8575 and PCF8575C provide general-purpose remote I/O
expansion for most microcontroller families via the I
2
C interface serial
clock (SCL) and serial data (SDA). These 16-bit I/O expanders for the
two-line bidirectional bus (I
2
C) are designed for 2.5-V to 5.5-V V
CC
operation (PCF8575) and 4.5-V to 5.5-V V
CC
operation (PCF8575C).
Key Features
• Two-wire I
2
C-bus to 16-bit bidirectional parallel-bus expander
• Addressed by three hardware-address pins
• Same fixed I
2
C address for PCF8575 and PCF8575C
Applications
• Fan control
• LED control
• System monitoring
• Push-button monitoring
• 8/16-bit bidirectional expansion
SOC:
Embedded
CPU
SRAM
Flash
SDRAM
CF
PCF8575
I/O
Expander
P[0:7]
Fan
LED
Indicators
P[10:17]
Key Pad
Micro-
controller
I
2
C Bus
PCF8575 typical application block diagram.
SOC
ASIC
CPU
MCU
SDA
SCL
INT
A0
A1
A2
LEDs
PCF8574/A
I/O expansion using TI’s PCF I
2
C logic.
Texas Instruments 1Q 2006
Audio Solutions Guide
➔