PCA9550 Philips Semiconductors, PCA9550 Datasheet - Page 9

• Manufacturer Part Number: PCA9550
• Description: 2-bit I2C LED driver with programmable blink rates
• Manufacturer: Philips Semiconductors

Philips Semiconductors
Programming example
The following example will show how to set LED0 to blink at 1 Hz at
a 50% duty cycle. LED1 will be set to blink at 4 Hz, 25% duty cycle.
Table 1.
2003 May 02
Start
PCA9550 address with A0 = LOW
PSC0 subaddress + auto-increment
Set prescaler PSC0 to achieve a period of 1 second:
Set PWM0 duty cycle to 50%:
Set prescaler PCS1 to achieve a period of 0.25
seconds:
Set PWM1 output duty cycle to 25%:
Set LED0 to PWM0 and set LED1 to blink at PWM1
Stop
2-bit I
256 – PWM0
256 – PWM1
Blink period + 1 + PSC0 ) 1
256
Blink period + 0.25 + PSC1 ) 1
256
2
PWM1 = 192
PWM0 = 128
C LED driver with programmable blink rates
PSC0 = 37
PSC1 = 9
+ 0.5
+ 0.25
38
38
I
S
COh
11h
25h
80h
09h
C0h
OEh
P
2
C-bus
9
PCA9550
Product data