pca9551bs3 NXP Semiconductors, pca9551bs3 Datasheet - Page 7

• Manufacturer Part Number: pca9551bs3
• Description: 8-bit I2c Led Driver With Programmable Blink Rates
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA9551_7
Product data sheet
6.3.6 LS0 to LS1 - LED selector registers
6.4 Pins used as GPIOs
6.5 Power-on reset
6.6 External RESET
The LSn LED select registers determine the source of the LED data.
Table 9.
Legend: * default value.
LED pins not used to control LEDs can be used as general purpose I/Os (GPIOs).
For use as input, set LEDn 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. LEDn 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.
When power is applied to V
a reset condition until V
and the PCA9551 registers are initialized to their default states, all the outputs in the
OFF state. Thereafter, V
A reset can be accomplished by holding the RESET pin LOW for a minimum of t
PCA9551 registers and I
RESET input is once again HIGH.
This input requires a pull-up resistor to V
Register
LS0 - LED0 to LED3 selector
LS0
LS1 - LED4 to LED7 selector
LS1
00 = output is set LOW (LED on)
01 = output is set high-impedance (LED off; default)
10 = output blinks at PWM0 rate
11 = output blinks at PWM1 rate
LS0 to LS1 - LED selector registers bit description
Bit
7:6
5:4
3:2
1:0
7:6
5:4
3:2
1:0
Rev. 07 — 23 February 2007
Value
01*
01*
01*
01*
01*
01*
01*
01*
DD
DD
2
C-bus state machine will be held in their default states until the
has reached V
DD
must be lowered below 0.2 V to reset the device.
, an internal Power-On Reset (POR) holds the PCA9551 in
8-bit I
Description
LED3 selected
LED2 selected
LED1 selected
LED0 selected
LED7 selected
LED6 selected
LED5 selected
LED4 selected
2
C-bus LED driver with programmable blink rates
DD
POR
if no active connection is used.
. At that point, the reset condition is released
PCA9551
© NXP B.V. 2007. All rights reserved.
w(rst)
. The
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