PCA9531 Datasheet, PDF (2/20 Pages) NXP Semiconductors – 8-bit I2C LED dimmer

Philips Semiconductors
8-bit I²C LED dimmer
Product data
PCA9531
FEATURES
• Eight LED drivers (on, off, flashing at a programmable rate)
• Two selectable, fully programmable blink rates (frequency and
duty cycle) between 0.625 and 160 Hz (1.6 and 6.25 milliseconds)
• 256 brightness steps
• Input/outputs not used as LED drivers can be used as regular
GPIOs
• Internal oscillator requires no external components
• I²C interface logic compatible with SMBus
• Internal power-on reset
• Noise filter on SCL/SDA inputs
• Active low reset input
• Eight open drain outputs directly drive LEDs to 25 mA
• Edge rate control on outputs
• No glitch on power-up
• Supports hot insertion
• Low stand-by current
• Operating power supply voltage range of 2.3 V to 5.5 V
• 0 to 400 kHz clock frequency
• ESD protection exceeds 2000 V HBM per JESD22-A114,
150 V MM per JESD22-A115 and 1000 V CDM per JESD22-C101
• Latch-up testing is done to JEDEC Standard JESD78 which
exceeds 100 mA
• Package offer: SO16, TSSOP16, HVQFN16
DESCRIPTION
The PCA9531 is an 8-bit I²C & SMBus I/O expander optimized for
dimming LEDs in 256 discrete steps for Red/Green/Blue (RGB)
color mixing and back light applications.
The PCA9531 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 can not 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 1.6
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 1.6 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,
push-buttons, alarm monitoring, fans, etc.
The active low hardware reset pin (RESET) and Power On Reset
(POR) initializes the registers to their default state causing the bits
to be set high (LED off).
Three hardware address pins on the PCA9531 allow eight devices
to operate on the same bus.
ORDERING INFORMATION
PACKAGES
TEMPERATURE RANGE
ORDER CODE
TOPSIDE MARK
16-pin plastic SO
-40 to +85 °C
PCA9531D
PCA9531D
16-pin plastic TSSOP
-40 to +85 °C
PCA9531PW
PCA9531
16-pin plastic HVQFN
-40 to +85 °C
PCA9531BS
9531
Standard packing quantities and other packaging data is available at www.philipslogic.com/packaging.
I²C is a trademark of Philips Semiconductors Corporation.
DRAWING NUMBER
SOT109-1
SOT403-1
SOT629-1
2003 Nov 10
2