PCA9553 Philips Semiconductors, PCA9553 Datasheet - Page 5

• Manufacturer Part Number: PCA9553
• Description: 4-bit I2C LED driver with programmable blink rates
• Manufacturer: Philips Semiconductors

Philips Semiconductors
PWM1 — PWM REGISTER 1
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
LS0 — LED SELECTOR
The LSx LED select registers determine the source of the LED data.
2004 Oct 01
default
default
4-bit I
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
bit
bit
2
7
1
7
0
LED3
C LED driver with programmable blink rates
6
0
6
1
5
0
5
0
LED2
4
0
4
1
256
3
0
3
0
LED 1
2
0
2
1
1
0
1
0
LED 0
0
0
0
1
5
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 V
the PCA9553 in a reset condition until V
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, V
DD
must be lowered below 0.2 V to reset the device.
DD
, an internal Power-On Reset holds
DD
has reached V
PCA9553
Product data sheet
POR
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