PCA9531 Datasheet, PDF (13/27 Pages) NXP Semiconductors – 8-bit I2C LED dimmer

NXP Semiconductors
PCA9531
8-bit I²C-bus LED dimmer
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 be dimmed at
25 % of their maximum brightness (duty cycle = 25 %).
Table 10. Programming PCA9531
Program sequence
START
PCA9531 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-
152
PSC0 = 151
Set PWM0 duty cycle to 50 %:
P_-----W2_---5--M_-6-----0_{- = 0.5}
PWM0 = 128
Set prescaler PCS1 to dim at maximum frequency:
Blink period = max
PSC1 = 0
Set PWM1 output duty cycle to 25 %:
P_-----W2_---5--M_-6-----1_{- = 0.25}
PWM1 = 64
Set LED0 to LED3 on
Set LED4 and LED5 to PWM0, and LED6 or LED7 to PWM1
STOP
I²C-bus
S
C0h
11h
97h
80h
00h
40h
55h
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
ground supply current
-
200
mA
P_tot
T_stg
T_amb
total power dissipation
storage temperature
ambient temperature
operating
-
400
mW
−65
+150 °C
−40
+85
°C
PCA9531_6
Product data sheet
Rev. 06 — 19 February 2009
© NXP B.V. 2009. All rights reserved.
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