2.4 A Two-Channel Flash LED Driver

The SKY81299 is a high-efficiency, 2.4 A high-current boost converter with two independently programmable constant current outputs. The device is intended for LED photo flash/facial recognition and “selfie” front-facing camera flash applications in all single-cell Li-ion powered portable products. The SKY81299 maintains the flash LED output current using a DC-DC step-up converter with a bypass function to maximize efficiency under all load conditions. The flash current for each channel can be programmed up to 1.5 A at 12 mA step. The device uses a common cathode (current source) topology to allow a direct flash LED cathode connection to the ground plane which facilitates LED heat dissipation. The total combined output current for flash outputs is 2.4 A.

The high-frequency 2.75 MHz DC-DC boost switching frequency allows the use of a small external inductor and output capacitor, which makes the SKY81299 ideally suited for small batterypowered applications. A startup control circuit automatically senses the flash LED forward voltage at any programmed output current setting and determines the most efficient operation mode.

An industry standard I2C digital interface is used to program the SKY81299 LED Flash and Movie modes. Device operations are fully configurable; Movie and Flash current level, current limits, and fault reporting are managed through I2C. Also included are separate flash enable inputs to initiate the flash operation and a flash inhibit input either to reduce the flash current to Moviemode levels or to shut off the flash current during high battery demand conditions.

The SKY81299 is available in a small 1.903 x 1.903 x 0.605 mm, 16-bump Wafer-Level Chip Scale (WLCSP) package.


Flash IOUT Total (mA)2400
Movie Mode IOUT Total (mA)250
LED Channels2
Min. VIN (V)2.5
Max. VIN (V)5.5
Max. VOUT (V)5.5
Max. Shutdown Current (μA)1
Typ. IQ (μA)1
Peak Efficiency93%
PackageWLCSP, 16-bump
Package (mm)1.9 x 1.9 x 0.605


  • Input voltage range: 2.5 V to 5.5 V
  • Each channel can program to 1.5 A with 12 mA programming
  • step size; up to 2.4 A total combined output current
  • >90% LED efficiency at 250 mA
      (3.3 V < VIN < 3.6 V, VF = 3.3 V);
    > 85% LED efficiency at 1 A
      (3.4 V< VIN < 3.9 V, VF = 3.3 V)
  • 2.75 MHz switching frequency
  • Soft-start and input current limit
  • Separate flash enable/flash inhibit
  • Programmable blinking LED notification
  • Industry standard 1 MHz I2C programming
    • Flash and Movie mode current
    • Input voltage monitor with programmable thresholds
    • Current read-back in input voltage monitor operation
    • Programmable safety timer
    • Fault read back
  • Fault protection
    • Integrated safety timer
    • Over-voltage (open LED, open circuit)
    • Short circuit
    • Over-temperature protection
    • Flash mode input voltage monitor
    • Open-drain fault output
  • -40 C to +85 C temperature range
  • Small WLCSP (16-bump, 1.903 x 1.903 x 0.605 mm, 0.4 mm pitch) package (MSL1, 260 ºC per JEDEC J-STD-020)

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