LED driver takes the strain off I²C bus

The PCA9550 from NXP Semiconductors is an I²C-controlled LED driver featuring two 25mA channels, with internal circuitry to control LED blinking without excessive traffic on the I²C bus.

An internal oscillator supporting two programmable blink rates allows the LEDs to be blinked at 0.172Hz or 44Hz after receiving only an initial set-up command across the bus. Compared to alternative devices that require repeated commands to turn LEDs off and on, the PCA9550 reduces bus traffic and frees the resources of the bus master.

The PCA9550 also implements an internal oscillator, as well as noise filtering on the I²C data and clock lines to enhance performance and save component count.

Integrated Power-On Reset (POR) circuitry and an external reset input allow internal registers to be cleared and the LEDs to be turned-off under hardware or software control.

 

FEATURES No glitch on power-up Supports hot insertion Low standby current Operating voltage range: 2.3V to 5.5V 400kHz maximum clock frequency

APPLICATIONS Instrument panels Status indicators Access control systems Medical equipment Handheld test equipment

 

 

• Rohm Electronics’ SML-P11 series, page 080514
• NEC Electronics’ µPD78F8024 8-bit MCU, page 080516

 

NXP PCA9550 I2C Controlled LED Driver