Datasheet

PCA9554_9554A All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 9 — 19 March 2013 6 of 35
NXP Semiconductors
PCA9554; PCA9554A
8-bit I
2
C-bus and SMBus I/O port with interrupt
5.2 Pin description
[1] HVQFN16 package die supply ground is connected to both V
SS
pin and exposed center pad. V
SS
pin must
be connected to supply ground for proper device operation. For enhanced thermal, electrical, and board
level performance, the exposed pad needs to be soldered to the board using a corresponding thermal pad
on the board and for proper heat conduction through the board, thermal vias need to be incorporated in the
PCB in the thermal pad region.
6. Functional description
Refer to Figure 1 “Block diagram of PCA9554/PCA9554A”.
6.1 Registers
6.1.1 Command byte
The command byte is the first byte to follow the address byte during a write transmission.
It is used as a pointer to determine which of the following registers will be written or read.
Table 3. Pin description
Symbol Pin Description
SO16, SSOP16,
TSSOP16
HVQFN16 SSOP20
A0 1 15 6 address input 0
A1 2 16 7 address input 1
A2 3 1 9 address input 2
IO0 4 2 10 input/output 0
IO1 5 3 11 input/output 1
IO2 6 4 12 input/output 2
IO3 7 5 14 input/output 3
V
SS
86
[1]
15 supply ground
IO4 9 7 16 input/output 4
IO5 10 8 17 input/output 5
IO6 11 9 19 input/output 6
IO7 12 10 20 input/output 7
INT
13 11 1 interrupt output (open-drain)
SCL 14 12 2 serial clock line
SDA 15 13 4 serial data line
V
DD
16 14 5 supply voltage
n.c. - - 3, 8, 13, 18 not connected
Table 4. Command byte
Command Protocol Function
0 read byte Input Port register
1 read/write byte Output Port register
2 read/write byte Polarity Inversion register
3 read/write byte Configuration register