AAT1265
Low Voltage 2MHz Step-Up DC/DC
Converter in SC70JW Package
Functional Block Diagram
VCC
VIN
OUT
Start-Up
Inrush Control
Low Voltage
Start-Up
VREF
Voltage
Reference
DH
Mode
Control
LX
2MHz
Logic
Oscillator
Current
Sense
Comp.
DL
Error
Amp.
GND
EN
GND
frequency modulation and low quiescent current
maintains this high efficiency for light load and
sleep mode conditions.
Functional Description
The AAT1265 synchronous step-up converter is
targeted for single- or dual-cell alkaline, NiMH, and
NiCd battery applications. It has a 1V typical start-
up voltage with operation after start-up to less than
0.8V.
In addition to the improved efficiency, the synchro-
nous boost has the added performance advantage
of true load disconnect during shutdown (<1µA
shutdown current), inrush current limit, and short-
circuit protection.
The high 2MHz switching frequency of the
AAT1265 facilitates output filter component size
reduction for improved power density and reduced
overall footprint. It also provides greater bandwidth
and improved transient response over other lower
frequency step-up converters. The compensation
and feedback is integrated with only three external
components (CIN, COUT, L).
PWM / PFM Control
The AAT1265 is a fixed frequency PWM peak cur-
rent mode control step-up converter. For light load
conditions (10 to 20mA and below), the converter
transitions to a variable frequency (PFM) mode to
reduce the dominant switching losses. In addition
to PFM operation, a zero current comparator
blocks reverse current in the P-channel synchro-
Low RDS(ON) synchronous power switches provide
high efficiency for heavy load conditions. Switching
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