PCA9553 데이터 시트보기 (PDF) - Philips Electronics

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PCA9553

4-bit I2C LED driver with programmable blink rates

Philips Electronics 

Philips Semiconductors

4-bit I2C LED driver with programmable blink rates

Product data sheet

PCA9553

PWM1 — PWM REGISTER 1

bit

7

6

5

4

3

2

1

0

default 1

0

0

0

0

0

0

0

The PWM1 register determines the duty cycle of BLINK1. The

outputs are LOW (LED off) when the count is less than the value in

PWM1 and HIGH when it is greater. If PWM1 is programmed with

00h, then the PWM1 output is always LOW.

The duty cycle of BLINK1 is:

256 – PWM1

256

LS0 — LED SELECTOR

LED3

LED2

LED 1

LED 0

bit

7

6

5

4

3

2

1

0

default 0

1

0

1

0

1

0

1

The LSx LED select registers determine the source of the LED data.

00 = Output is set LOW (LED on)

01 = Output is set Hi-Z (LED off – default)

10 = Output blinks at PWM0 rate

11 = Output blinks at PWM1 rate

PINS USED AS GENERAL PURPOSE I/Os

LED pins not used to control LEDs can be used as general purpose

I/Os.

For use as input: Set LEDx to high-impedance (01) and then read

the pin state via the input register.

For use as output: Connect external pull-up resistor to the pin and

size it according to the DC recommended operating characteristics.

LED output pin is HIGH when the output is programmed as

high-impedance, and LOW when the output is programmed LOW

through the “LED selector” register. The output can be pulse-width

controlled when PWM0 or PWM1 are used.

POWER-ON RESET

When power is applied to VDD, an internal Power-On Reset holds

the PCA9553 in a reset condition until VDD has reached VPOR. At

this point, the reset condition is released and the PCA9553 registers

are initialized to their default states, with all outputs in the off state.

Thereafter, VDD must be lowered below 0.2 V to reset the device.

2004 Oct 01

5

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