RT9902/DS9902 pdf datasheet (4

The RT9902 is a complete power supply solution for digital
still cameras and other hand-held devices. It integrates a
high-efficiency main step-up DC-DC converter, two highefficiency
step-down converters, a charge pump, and a
linear controller that drives an external P-Channel
MOSFET for linear regulator. The RT9902 is targeted for
applications that use either two or three AA cells or a single
lithiumion battery.
The main step-up DC-DC converter accepts inputs from
1.5V to 5.5V and build in 2.6A Internal switch. The two
step-down DC-DC converters (CH2, CH3) accept inputs
from 1.5V to 5.5V and regulate a resistor adjustable
output from 0.8V to 5.5V. Each DC-DC converter has
independent shutdown input.
The feature of the charge pump is to deliver few current
to micro-controller when the system operates in the
standby mode. RT9902 includes a linear controller with
0.8V reference voltage. An adjustable operating frequency
(up to 1.4MHz) is utilized to get optimum size, cost, and
efficiency.
RT9902 is available in VQFN-32L 5x5 package.