PCA9553 Philips Semiconductors, PCA9553 Datasheet - Page 4

• Manufacturer Part Number: PCA9553
• Description: 4-bit I2C LED driver with programmable blink rates
• Manufacturer: Philips Semiconductors

Philips Semiconductors
DEVICE ADDRESSING
Following a START condition the bus master must output the
address of the slave it is accessing. The address of the PCA9553/01
is shown in Figure 3 and PCA9553/02 in Figure 4.
The last bit of the address byte defines the operation to be
performed. When set to logic 1 a read is selected, while a logic 0
selects a write operation.
CONTROL REGISTER
Following the successful acknowledgement of the slave address,
the bus master will send a byte to the PCA9553 which will be stored
in the Control Register.
The lowest 3 bits are used as a pointer to determine which register
will be accessed.
If the auto-increment flag is set, the three low order bits of the
Control Register are automatically incremented after a read or write.
This allows the user to program the registers sequentially. The contents
of these bits will rollover to ‘000’ after the last register is accessed.
When auto-increment flag is set (AI = 1) and a read sequence is
initiated, the sequence must start by reading a register different from
‘0’ (B2 B1 B0
Only the 3 least significant bits are affected by the AI flag.
Unused bits must be programmed with zeroes.
2004 Oct 01
4-bit I
RESET STATE: 00h
2
Figure 3. Slave address — PCA9553/01
Figure 4. Slave address — PCA9553/02
C LED driver with programmable blink rates
0 0 0)
0
1
1
Figure 5. Control register
0
1
1
0
SLAVE ADDRESS
SLAVE ADDRESS
0
0
AUTO-INCREMENT FLAG
AI
0
0
0
0
0
B2
1
1
REGISTER ADDRESS
0
1
B1
R/W
R/W
B0
SW01034
SW01037
SW01038
4
Control Register definition
REGISTER DESCRIPTION
INPUT — INPUT REGISTER
The INPUT register reflects the state of the device pins. Writes to
this register will be acknowledged but will have no effect.
NOTE: The default value “X” is determined by the externally applied
logic level, normally ‘1’ when used for directly driving LED with
pull-up to V
PSC0 — FREQUENCY PRESCALER 0
PSC0 is used to program the period of the PWM output.
The period of BLINK0
PWM0 — PWM REGISTER 0
The PWM0 register determines the duty cycle of BLINK0. The
outputs are LOW (LED off) when the count is less than the value in
PWM0 and HIGH when it is greater. If PWM0 is programmed with
00h, then the PWM0 output is always LOW.
The duty cycle of BLINK0 is: 256 – PWM0
PSC1 — FREQUENCY PRESCALER 1
PSC1 is used to program the period of PWM output.
The period of BLINK1
default
default
default
default
B2
0
0
0
0
1
1
bit
bit
bit
bit
B1
0
0
1
1
0
0
DD
7
0
7
1
7
1
7
1
.
B0
0
1
0
1
0
1
6
0
6
1
6
0
6
1
REGISTER
INPUT
PWM0
PWM1
NAME
PSC0
PSC1
LS0
(PSC0
(PSC1
5
0
5
1
5
0
5
1
44
44
4
0
4
1
4
0
4
1
256
1)
1)
WRITE
WRITE
WRITE
WRITE
WRITE
READ/
READ/
READ/
READ/
READ/
READ
TYPE
LED
X
3
3
3
1
3
0
3
1
PWM REGISTER 0
PWM REGISTER 1
LED
INPUT REGISTER
PCA9553
LED SELECTOR
X
2
2
2
1
2
0
2
1
PRESCALER 0
PRESCALER 1
Product data sheet
FREQUENCY
FREQUENCY
REGISTER
FUNCTION
LED
1
1
X
1
1
1
0
1
1
LED
0
0
X
0
1
0
0
0
1