AAT1265 AAT, AAT1265 Datasheet - Page 8

• Manufacturer Part Number: AAT1265
• Description: Step-Up DC/DC Converter
• Manufacturer: AAT

Functional Block Diagram
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.
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 (C
Low R
high efficiency for heavy load conditions. Switching
8
DS(ON)
synchronous power switches provide
IN
, C
OUT
GND
, L).
VCC
Reference
Voltage
Amp.
Error
V
Current
Sense
REF
Inrush Control
Start-Up
Oscillator
Control
Mode
2MHz
Comp.
EN
Low Voltage 2MHz Step-Up DC/DC
frequency modulation and low quiescent current
maintains this high efficiency for light load and
sleep mode conditions.
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.
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 Voltage
Start-Up
Converter in SC70JW Package
Logic
VIN
DH
DL
OUT
GND
LX
1265.2006.05.1.1