PCA9552 Datasheet, PDF (6/21 Pages) NXP Semiconductors – 16-bit I2C LED driver with programmable blink rates

Philips Semiconductors
16-bit I²C LED driver with programmable blink rates
Product data sheet
PCA9552
PWM0 — PWM REGISTER 0
bit
7
6
5
4
3
2
1
0
default 1
0
0
0
0
0
0
0
The PWM0 register determines the duty cycle of BLINK0. The
outputs are LOW (LED off) when the count is less than the value in
PWM0 and HIGH when it is greater. If PWM0 is programmed with
00h, then the PWM0 output is always LOW.
The duty cycle of BLINK0 is:
256 – PWM0
256
PSC1 — FREQUENCY PRESCALER 1
bit
7
6
5
4
3
2
1
0
default 1
1
1
1
1
1
1
1
PSC1 is used to program the period of PWM output.
The
period
of
BLINK1
+
(PSC1 ) 1)
44
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 0–3 SELECTOR
LED 3
LED 2
LED 1
bit
7
6
5
4
3
2
default 0
1
0
1
0
1
LED 0
1
0
0
1
LS1 — LED 4–7 SELECTOR
LED 7
LED 6
bit
7
6
5
4
default 0
1
0
1
LED 5
3
2
0
1
LED 4
1
0
0
1
LS2 — LED 8–11 SELECTOR
LED 11
LED 10
bit
7
6
5
4
default 0
1
0
1
LED 9
3
2
0
1
LED 8
1
0
0
1
LS3 — LED 12–15 SELECTOR
LED 15
LED 14
bit
7
6
5
4
default 0
1
0
1
LED 13
3
2
0
1
LED 12
1
0
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 V_DD, an internal Power-On Reset holds
the PCA9552 in a reset condition until V_DD has reached V_POR. At
this point, the reset condition is released and the PCA9552 registers
are initialized to their default states, all the outputs in the off state.
Thereafter, V_DD must be lowered below 0.2 V to reset the device.
EXTERNAL RESET
A reset can be accomplished by holding the RESET pin LOW for a
minimum of t_W. The PCA9552 registers and I²C state machine will
be held in their default state until the RESET input is once again
HIGH.
This input requires a pull-up resistor to V_DD if no active connection is
used.
2004 Oct 01
6