PCA9531

General description

The PCA9531 is an 8-bit I²C-bus and 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 cannot 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 1.69 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 1.69 second the bus master (MCU, MPU, DSP, chip set, etc.) must send repeated commands to turn the LED on and off as is currently done when using normal I/O expanders like the NXP Semiconductors 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.

Features

• Eight LED drivers (on, off, flashing at a programmable rate)
• Two selectable, fully programmable blink rates (frequency and duty cycle) between 0.59 Hz and 152 Hz (1.69 second and 6.58 milliseconds)
• 256 brightness steps
• Input/outputs not used as LED drivers can be used as regular GPIOs
• Internal oscillator requires no external components
• I²C-bus 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 standby current
• Operating power supply voltage range of 2.3 V to 5.5 V
• 0 Hz 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
• Packages offered: SO16, TSSOP16, HVQFN16

Products/packages

Quality/reliability/chemical content

Quality and reliability disclaimer

Pricing/ordering/availability

Applications

Related applications
Intelligent washing machine
Intelligent washing machine
PCI analog/DVB-T stereo TV receiver
Transceiver board
Power amplifier board
Main CPU board
Set-top box - MMS functionality
Color mixing for RGBA LEDs

Block diagrams/pinning

Design support

Application Notes

AN10397_1; How to use the SC18IM700 to control any I2C-bus device (2005-12-05)

AN10315_1; LED dimmer demoboard (2005-01-11)

AN10441_1; Level shifting techniques in I2C-bus design (2007-06-20)

AN10148_4; PCA9564 - I2C-bus controller (2004-11-22)

AN10149_2; PCA9564 Evaluation Board (2004-08-19)

Support Documents

75016543; An industry-leading portfolio of cost-effective, power-saving solutions for major home appliances (2008-06-01)

UM10206_1; I2C Demonstration Board 2005-1 Quick Start Guide (2006-06-13)

UM10204_3; I2C-bus specification and user manual (2007-06-26)

web; IBIS and HSPICE Model ()

75016073; NXP 2/4/8/16-bit I2C/SMBus LED dimmers PCA9530/31/32/33 (2007-06-01)

75015692; NXP LED dimmer demonstration board OM6279 (2006-11-01)

75015963; NXP evaluation kit for PCA9564 (2007-05-01)

UM10317_1; PCA9633 demonstration board OM6282 (2008-12-15)

Parametrics/similar products

Similar products
PCA9531 links to the similar products page containing an overview of products that are similar in function or related to the type number(s) as listed on this page. The similar products page includes products from the same catalog tree(s), relevant selection guides and products from the same functional category.

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Disclaimers

• General product disclaimer
• Quality and reliability disclaimer