SKY81298

2.4 A Three-Channel Flash LED Driver with I<sup>2</sup>C Control Interface

The SKY81298 is a high-efficiency, high-current boost converter with three independently programmable constant current outputs. The device is optimized for LED flash applications implementing tri-tone flash LED color compensation, or dual rear LED flash plus single front LED flash to support “selfie” pictures taken from the front-facing camera. The SKY81298 uses a single DC/DC boost and only one inductor to support all three LED outputs, and all LED outputs may be enabled simultaneously to support up to a total of 2.4 A total LED current.

The SKY81298 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 SKY81298 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 SKY81298 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 flash enable inputs can be configured to control different flash LEDs as required by the system designer.

The SKY81298 is available in a small 1.903 x 1.903 x 0.605 mm, 16-bump Wafer-Level Chip Scale (WLCSP) package.

Product Summary

Talk to Sales ECAD Model

Specifications

Flash I_OUT Total (mA)2400

Movie Mode I_OUT Total (mA)250

LED Channels3

Min. V_IN (V)2.5

Max. V_IN (V)5.5

Max. V_OUT (V)5.5

InterfaceI²C

Max. Shutdown Current (μA)1

Typ. I_Q (μA)1

Peak Efficiency93%

PackageWLCSP, 16-bump

Package (mm)1.9 x 1.9 x 0.605

PackageWLCSP-16

Features

Input voltage range: 2.5 V to 5.5 V
Each channel can program up to 1.5 A with 12 mA 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
Temperature range: −40 C to +85 C
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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