The SKY81292 is a high-efficiency, 1.8 A high-current boost
converter with a programmable constant current. The device is
intended for LED photo flash applications in all single-cell Li-ion
powered portable products.
The SKY81292 maintains the flash LED output current using a DCDC
step-up converter with a bypass function to maximize
efficiency when under all load conditions. For single flash LED
applications, the flash current can be programmed up to 1.8 A.
For dual flash LED applications, the flash current can be
programmed up to 900 mA. This provides a direct flash LED
cathode connection to the ground plane that helps heat
The high frequency 2 MHz DC-DC boost switching frequency
allows the use of a small external inductor and output capacitor,
which makes the SKY81292 ideally suited for small batterypowered
applications. A start-up 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
SKY81292 LED flash and movie modes. Device operations are
fully configurable; movie and flash current level, current limits,
and fault reporting. Also included is a separate flash enable input
to initiate the flash operation and a flash inhibit input to reduce the
flash current to movie-mode levels during high battery demand
conditions. An additional low-level programmable current source
output is provided to drive an LED indicator lamp.
The integrated thermal management system protects the device in
the event of an output short-circuit condition. An NTC thermistor
function protects the external flash LEDs from thermal damage.
Fault status may be read using the I2C interface after the system is
alerted by an open drain fault flag. Built-in soft-start circuitry
prevents excessive in-rush current during start-up. The shutdown
feature reduces quiescent current to less than 1.0 μA.
The SKY81292 is provided in a small, 16-bump, 2 mm x 2 mm
Wafer Level Chip Scale Package (WLCSP).