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PCA9531PW

8-bit I2C LED dimmer

Philips Electronics 

Philips Semiconductors

8-bit I2C LED dimmer

Product data

PCA9531

FEATURES

• Eight LED drivers (on, off, flashing at a programmable rate)

• Two selectable, fully programmable blink rates (frequency and

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

• 256 brightness steps

• Input/outputs not used as LED drivers can be used as regular

GPIOs

• Internal oscillator requires no external components

• I2C interface logic compatible with SMBus

• Internal power-on reset

• Noise filter on SCL/SDA inputs

• Active low reset input

• Eight open drain outputs directly drive LEDs to 25 mA

• Edge rate control on outputs

• No glitch on power-up

• Supports hot insertion

• Low stand-by current

• Operating power supply voltage range of 2.3 V to 5.5 V

• 0 to 400 kHz clock frequency

• ESD protection exceeds 2000 V HBM per JESD22-A114,

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

• Latch-up testing is done to JEDEC Standard JESD78 which

exceeds 100 mA

• Package offer: SO16, TSSOP16, HVQFN16

DESCRIPTION

The PCA9531 is an 8-bit I2C & SMBus I/O expander optimized for

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

16-pin plastic SO

-40 to +85 °C

PCA9531D

PCA9531D

16-pin plastic TSSOP

-40 to +85 °C

PCA9531PW

PCA9531

16-pin plastic HVQFN

-40 to +85 °C

PCA9531BS

9531

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

I2C is a trademark of Philips Semiconductors Corporation.

DRAWING NUMBER

SOT109-1

SOT403-1

SOT629-1

2003 Nov 10

2

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