Philips Semiconductors

Product data sheet

PCA9533

2

2004 Oct 01

FEATURES

cycle) between 0.591 Hz and 152 Hz (1.69 seconds and

6.58 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 PCA9533 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 cannot 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

1.69 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 1.69 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,

pushbuttons, alarm monitoring, fans, etc.

Power-On Reset (POR) initializes the registers to their default state

causing the bits to be set HIGH (LED off).

Due to pin limitations, the PCA9533 is not featured with hardware

address pins. The PCA9533/01 and the PCA9533/02 have different

PIN CONFIGURATION

1

2

3

45

6

7

8

LED0

LED1

LED2

SDA

SCL

LED3

SW01035

Figure 1. Pin configuration

PIN DESCRIPTION

PIN

NUMBER

SYMBOL

FUNCTION

1

LED0

LED driver 0

2

LED1

LED driver 1

3

LED2

LED driver 2

4

Supply ground

5

LED3

LED driver 3

6

SCL

Serial clock line

7

SDA

Serial data line

8

Supply voltage