DESCRIPTION
The PCA9553 LED Blinker blinks LEDs in I2C 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. The PCA9553 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). 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.

FEATURES
• 4 LED drivers (on, off, flashing at a programmable rate)
• 2 selectable, fully programmable blink rates (frequency and duty
   cycle) between 0.172 Hz and 44 Hz (5.82 and 0.023 seconds)
• Input/outputs not used as LED drivers can be used as regular GPIOs
• Internal oscillator requires no external components
• I2C-businterface logic compatible with SMBus
• Internal power-on reset
• Noise filter on SCL/SDA inputs
• 4 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 (MSOP8)