PCA9551

General description

The PCA9551 LED blinker blinks LEDs in I²C-bus and SMBus applications where it is necessary to limit bus traffic or free up the I²C-bus master's (MCU, MPU, DSP, chip set, etc.) timer. The uniqueness of this device is the internal oscillator with two programmable blink rates. To blink LEDs using normal I/O expanders like the PCF8574 or PCA9554, the bus master must send repeated commands to turn the LED on and off. This greatly increases the amount of traffic on the I²C-bus and uses up one of the master's timers. The PCA9551 LED blinker instead requires only the initial set-up command to program BLINK RATE 1 and BLINK RATE 2 (i.e., the frequency and duty cycle) for each individual output. From then on, only one command from the bus master is required to turn each individual open-drain output on, off, or to cycle at BLINK RATE 1 or BLINK RATE 2. Maximum output sink current is 25 mA per bit and 100 mA per package.

Any bits not used for controlling the LEDs can be used for General Purpose parallel Input/Output (GPIO) expansion.

The active LOW hardware reset pin (RESET) and Power-On Reset (POR) initializes the registers to their default state, all zeroes, causing the bits to be set HIGH (LED off).

Three hardware address pins on the PCA9551 allow eight devices to operate on the same bus.

The newer Fast-mode Plus PCA9634 8-bit LED controller offers an individual PWM dimming control for each channel for better color mixing capabilities with a global PWM for dimming or blinking all channels at the same time. There are 126 possible address combinations and the maximum output sink current is 25 mA per bit and 200 mA per package.

Features

• 8 LED drivers (on, off, flashing at a programmable rate)
• 2 selectable, fully programmable blink rates (frequency and duty cycle) between 0.148 Hz and 38 Hz (6.74 seconds and 0.026 seconds)
• 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
• 8 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

AN264; I2C Devices for LED Display Control (2002-07-22)

AN10146_02; I2C 2002-1A Evaluation Board (2003-02-26)

AN10216_1; I2C manual (2003-03-27)

AN10216_1; I2C manual (2003-03-27)

AN10216_1; I2C manual (2003-03-27)

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

Support Documents

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

design_con_2003_tecforum_i2c_bus_overview; DesignCon 2003 TecForum I 2 C Bus Overview (2003-01-27)

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

i2c_overview_2h_2003; I2C Overview 2H 2003 ()

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

web; IBIS and HSPICE Model ()

75016021; NXP 2/4/8/16-bit I2C/SMBus LED blinkers PCA9550/51/52/53 (2007-06-01)

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

75016531; NXP I2C 2002-1A evaluation board kits OM6285 and OM6278 (2008-07-01)

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

Parametrics/similar products

Similar products
PCA9551 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