PCA9551D-T Datasheet, PDF (12/26 Pages) NXP Semiconductors – 8-bit I2C-bus LED driver with programmable blink rates

NXP Semiconductors
PCA9551
8-bit I²C-bus LED driver with programmable blink rates
8.2 Programming example
The following example will show how to set LED0 to LED3 on. It will then set LED4 and
LED5 to blink at 1 Hz at a 50 % duty cycle. LED6 and LED7 will be set to blink at 4 Hz and
at a 25 % duty cycle.
Table 10. Programming PCA9551
Program sequence
START
PCA9551 address with A0 to A2 = LOW
PSC0 subaddress + Auto-Increment
Set prescaler PSC0 to achieve a period of 1 second:
Blink period = 1 = ^P-----^S---^C----⁰-----⁺-----¹-
38
PSC0 = 37
Set PWM0 duty cycle to 50 %:
2_---5_---6_-----–_-2---5P---6-W_------M_-----0_{-- = 0.5}
PWM0 = 128
Set prescaler PSC1 to achieve a period of 0.25 seconds:
Blink period = 0.25 = ^P-----^S---^C--₃--¹-₈----⁺-----¹-
PSC1 = 9
Set PWM1 output duty cycle to 25 %:
2_---5_---6_-----–_-2---5P---6-W_------M_-----1_{-- = 0.25}
PWM1 = 192
Set LED0 to LED3 on
Set LED4 and LED5 to PWM0, and LED6 or LED7 to PWM1
STOP
I²C-bus
S
C0h
11h
25h
80h
09h
C0h
00h
FAh
P
9. Limiting values
Table 11. Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol Parameter
Conditions
Min
Max Unit
V_DD
V_I/O
I_O(LEDn)
supply voltage
voltage on an input/output pin
output current on pin LEDn
−0.5
+6.0 V
V_SS − 0.5 5.5
V
-
±25
mA
I_SS
P_tot
T_stg
T_amb
ground supply current
total power dissipation
storage temperature
ambient temperature
operating
-
100
mA
-
400
mW
−65
+150 °C
−40
+85
°C
PCA9551_8
Product data sheet
Rev. 08 — 31 July 2008
© NXP B.V. 2008. All rights reserved.
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