Philips Semiconductors

Product data

PCA9531

2

2003 Nov 10

FEATURES

duty cycle) between 0.625 and 160 Hz (1.6 and 6.25 milliseconds)

GPIOs

150 V MM per JESD22-A115 and 1000 V CDM per JESD22-C101

exceeds 100 mA

DESCRIPTION

dimming LEDs in 256 discrete steps for Red/Green/Blue (RGB)

color mixing and back light applications.

The PCA9531 contains an internal oscillator with two user

programmable blink rates and duty cycles coupled to the output

PWM. The LED brightness is controlled by setting the blink rate high

enough (> 100 Hz) that the blinking can not be seen and then using

the duty cycle to vary the amount of time the LED is on and thus the

average current through the LED.

The initial setup sequence programs the two blink rates/duty cycles

for each individual PWM. From then on, only one command from the

bus master is required to turn individual LEDs ON, OFF, BLINK

RATE 1 or BLINK RATE 2. Based on the programmed frequency

and duty cycle, BLINK RATE 1 and BLINK RATE 2 will cause the

LEDs to appear at a different brightness or blink at periods up to 1.6

second. The open drain outputs directly drive the LEDs with

maximum output sink current of 25 mA per bit and 100 mA per

package.

To blink LEDs at periods greater than 1.6 second the bus master

(MCU, MPU, DSP, chipset, etc.) must send repeated commands to

turn the LED on and off as is currently done when using normal I/O

Expanders like the Philips PCF8574 or PCA9554. Any bits not used

for controlling the LEDs can be used for General Purpose Parallel

Input/Output (GPIO) expansion which provides a simple solution

when additional I/O is needed for ACPI power switches, sensors,

push-buttons, alarm monitoring, fans, etc.

The active low hardware reset pin (RESET) and Power On Reset

(POR) initializes the registers to their default state causing the bits

to be set high (LED off).

Three hardware address pins on the PCA9531 allow eight devices

to operate on the same bus.

ORDERING INFORMATION

PACKAGES

TEMPERATURE RANGE

ORDER CODE

TOPSIDE MARK

DRAWING NUMBER

16-pin plastic SO

-40 to +85

°C

PCA9531D

PCA9531D

SOT109-1

16-pin plastic TSSOP

-40 to +85

°C

PCA9531PW

PCA9531

SOT403-1

16-pin plastic HVQFN

-40 to +85

°C

PCA9531BS

9531

SOT629-1

Standard packing quantities and other packaging data is available at www.philipslogic.com/packaging.