PCA9553 Datasheet, PDF (4/18 Pages) NXP Semiconductors – 4-bit I2C LED driver with programmable blink rates

Philips Semiconductors
4-bit I²C LED driver with programmable blink rates
Product data sheet
PCA9553
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.
SLAVE ADDRESS
1 1 0 0 0 1 0 R/W
SW01037
Figure 3. Slave address — PCA9553/01
SLAVE ADDRESS
1 1 0 0 0 1 1 R/W
SW01038
Figure 4. Slave address — PCA9553/02
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.
0 0 0 AI 0 B2 B1 B0
RESET STATE: 00h
REGISTER ADDRESS
AUTO-INCREMENT FLAG
Figure 5. Control register
SW01034
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 0 0 0 0)
Only the 3 least significant bits are affected by the AI flag.
Unused bits must be programmed with zeroes.
Control Register definition
B2
B1
B0
REGISTER
NAME
TYPE
000
INPUT
READ
001
PSC0
READ/
WRITE
010
PWM0
READ/
WRITE
011
PSC1
READ/
WRITE
100
PWM1
READ/
WRITE
101
LS0
READ/
WRITE
REGISTER
FUNCTION
INPUT REGISTER
FREQUENCY
PRESCALER 0
PWM REGISTER 0
FREQUENCY
PRESCALER 1
PWM REGISTER 1
LED SELECTOR
REGISTER DESCRIPTION
INPUT — INPUT REGISTER
LED LED LED LED
3
2
1
0
bit
7
6
5
4
3
2
1
0
default 0
0
0
0
X
X
X
X
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_DD.
PSC0 — FREQUENCY PRESCALER 0
bit
7
6
5
4
3
2
1
0
default 1
1
1
1
1
1
1
1
PSC0 is used to program the period of the PWM output.
The
period
of
BLINK0
+
(PSC0 )
44
1)
PWM0 — PWM REGISTER 0
bit
7
6
5
4
3
2
1
0
default 1
0
0
0
0
0
0
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
256
PSC1 — FREQUENCY PRESCALER 1
bit
7
6
5
4
3
2
1
0
default 1
1
1
1
1
1
1
1
PSC1 is used to program the period of PWM output.
The
period
of
BLINK1
+
(PSC1 )
44
1)
2004 Oct 01
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