AAT1230 Datasheet, PDF (8/21 Pages) Advanced Analogic Technologies – 18V 100mA Step-Up Converter

Functional Block Diagram
VP
AAT1230
18V 100mA Step-Up Converter
VIN
LIN
EN/SET
FB1
FB2
SEL
Soft-Start
Timer
V_REF1
V_REF2
Control
Output
Select
GND
SW
PGND
Functional Description
The AAT1230 consists of a DC/DC boost controller,
an integrated slew rate controlled input disconnect
MOSFET switch, and a MOSFET power switch. A
high voltage rectifier, power inductor, output capac-
itor, and resistor divider network are required to
implement a DC/DC boost converter.
Control Loop
The AAT1230 provides the benefits of current mode
control with a simple hysteretic feedback loop. The
device maintains exceptional DC regulation, tran-
sient response, and cycle-by-cycle current limit with-
out additional compensation components.
8
The AAT1230 modulates the power MOSFET
switching current in response to changes in output
voltage. This allows the voltage loop to directly
program the required inductor current in response
to changes in the output load.
The switching cycle initiates when the N-channel
MOSFET is turned ON and current ramps up in the
inductor. The ON interval is terminated when the
inductor current reaches the programmed peak
current level. During the OFF interval, the input
current decays until the lower threshold, or zero
inductor current, is reached. The lower current is
equal to the peak current minus a preset hystere-
sis threshold - which determines the inductor ripple
current. The peak current is adjusted by the con-
troller until the output current requirement is met.
1230.2006.03.1.0