24-Channel SPI Serial Bus 32 MA/5.5 V Constant-Current LED Driver

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Block Diagram

PCA9957 Block diagram

PCA9957 Block diagram


  • 24 LED drivers. Each output programmable at:
    • Off
    • On
    • 8 bits programmable LED brightness
    • 8 bits programmable group dimming/blinking mixed with individual LED brightness
    • Programmable LED output delay to reduce EMI and surge currents
  • Gradation control for all channels
    • Each channel can be assigned to one of six gradation control groups
    • Programmable gradation time and rate for ramp-up and/or ramp-down operations
    • Programmable step time (6-bit) from 0.5 ms (minimum) to 512 ms (maximum)
    • Programmable hold-on time after ramp-up and hold-off time after ramp-down (3-bit) from 0 s to 6 s
    • Programmable final ramp-up and hold-on current
    • Programmable brightness current output adjustment, either linear or exponential curve
  • 24 constant current output channels can sink up to 32 mA, and tolerate up to 5.5 V when OFF
  • Output current adjusted through an external resistor (REXT input)
  • Output current accuracy
    • ±6.5 % absolute accuracy with 30 mA output current
    • Maximum ±4 % channel to channel variation
    • Maximum ±6 % device to device variation
  • Open/short load/overtemperature detection mode to detect individual LED errors
  • 4-wire serial bus interface with 10 MHz data clock rate
  • 256-step (8-bit) linear programmable brightness per LED output varying from fully off (default) to maximum brightness fully ON using a 31.25 kHz PWM signal
  • 256-step group brightness control allows general dimming (using a 122 Hz PWM signal) from fully off to maximum brightness (default)
  • 256-step group blinking with frequency programmable from 15 Hz to 16.8 s and duty cycle from 0 % to 99.6 %
  • Active LOW Output Enable (OE) input pin allows for hardware blinking and dimming of the LEDs
  • 8 MHz internal oscillator requires no external components
  • Internal power-on reset
  • No glitch on LEDn outputs on power-up
  • Low standby current
  • Operating power supply voltage (VDD) range of 2.7 V to 5.5V
  • 5.5 V tolerant inputs on non-LED pins
  • -40 °C to +85 °C operation
  • Latch-up performance exceeds 100 mA per JESD 78, Class II
  • ESD protection exceeds
    • 2 kV Human-Body Model (A114-A)
    • 1 kV Charged-Device Model (C101)
  • Package offered: HVQFN40

Part numbers include: PCA9957HN, OMPCA9957LEDEV.


Quick reference to our documentation types.

3 documents

Design Resources


2 hardware offerings


2 software files

Note: For better experience, software downloads are recommended on desktop.


1 trainings


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