DESCRIPTION
The PCA9550 LED Blinker blinks LEDs in I2C-bus and SMBus applications where it is necessary to limit bus traffic or free up the I2C Master’s (MCU, MPU, DSP, chipset, 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.

FEATURES
• 2 LED drivers (on, off, flashing at a programmable rate)
• 2 selectable, fully programmable blink rates (frequency and duty cycle) between 0.15625 and 40 Hz (6.4 and 0.025 seconds)
• Input/output 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
• 2 open drain outputs directly drive LEDs to 25 mA
• Controlled edge rates to minimize ground bounce
• 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
• Packages offered: SO8, TSSOP8