PCA9531D datasheet(13/27 Pages) NXP

13 / 27 page

PCA9531_6

Product data sheet

Rev. 06 — 19 February 2009

13 of 27

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 %).

Limiting values

Table 10.

Programming PCA9531

Program sequence

I2C-bus

START

PCA9531 address with A0 to A2 = LOW

C0h

PSC0 subaddress + Auto-Increment

11h

Set prescaler PSC0 to achieve a period of 1 second:

PSC0 = 151

97h

Set PWM0 duty cycle to 50 %:

PWM0 = 128

80h

Set prescaler PCS1 to dim at maximum frequency:

PSC1 = 0

00h

Set PWM1 output duty cycle to 25 %:

PWM1 = 64

40h

Set LED0 to LED3 on

55h

Set LED4 and LED5 to PWM0, and LED6 or LED7 to PWM1

FAh

STOP

Blink period

PSC0

152

------------------------

PWM 0

256

-----------------

0.5

Blink period

max

PWM 1

256

-----------------

0.25

Table 11.

Limiting values

In accordance with the Absolute Maximum Rating System (IEC 60134).

Symbol

Parameter

Conditions

Min

Max

Unit

VDD

supply voltage

−0.5

+6.0

VI/O

voltage on an input/output pin

VSS − 0.5

5.5

IO(LEDn)

output current on pin LEDn

±25

ISS

ground supply current

200

Ptot

total power dissipation

400

Tstg

storage temperature

−65

+150

°C

Tamb

ambient temperature

operating

−40

+85

°C

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