pcf8575cts-1 NXP Semiconductors, pcf8575cts-1 Datasheet - Page 6

• Manufacturer Part Number: pcf8575cts-1
• Description: Remote 16-bit I/o Expander For I2c-bus
• Manufacturer: NXP Semiconductors

Philips Semiconductors
6
6.1
The 16 ports (see Fig.3) are entirely independent and can be used either as input or output ports. Input data is transferred
from the ports to the microcontroller in the READ mode (see Fig.6). Output data is transmitted to the ports in the WRITE
mode (see Fig.5).
This quasi-bidirectional I/O can be used as an input or output without the use of a control signal for data direction.
At power-on all the I/Os are in 3-state mode. The strong pull-up to V
loaded output. This strong pull-up turns on when the output is written HIGH, and is switched off by the negative edge of
SCL. After this short period the output is in 3-state mode. The I/O should be written HIGH before being used as an input.
After power-on as all the I/Os are set to 3-state all of them can be used as inputs. Any change in setting of the I/Os as
either inputs or outputs can be done with the write mode. Warning: If a HIGH is applied to an I/O which has been written
earlier to LOW, a large current (I
6.2
Figures 4, 5 and 6 show the address and timing diagrams. Before any data is transmitted or received the master must
send the address of the receiver via the SDA line. The first byte transmitted after the START condition carries the address
of the slave device and the read/write bit. The address of the slave device must not be changed between the START and
the STOP conditions. The PCF8575C acts as a slave receiver or a slave transmitter.
1999 Aug 05
handbook, full pagewidth
Remote 16-bit I/O expander for I
FUNCTIONAL DESCRIPTION
Quasi-bidirectional I/Os
Addressing
write pulse
data from
shift register
power-on
reset
read pulse
data to
shift register
Fig.4 Byte containing the slave address and the R/W bits.
handbook, halfpage
OL
) will flow to V
Fig.3 Simplified schematic diagram of each I/O.
S
C I
D
FF
S
0
Q
SS
1
2
(see Chapter 10; note 3).
slave address
C-bus
0
C I
D
FF
S
0
Q
6
A2
I OHt
A1
DD
A0 R/W
(I
OHt
MGL541
) allows a fast rising edge into a heavily
A
I OL
MGS632
V DD
V SS
P00 to P07
P10 to 17
to interrupt
logic
Product specification
PCF8575C