herunterladen
FAN2011/FAN2012 Rev. 1.0.3
1
www.fairchildsemi.com
January 2005
FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
FAN2011/FAN2012
1.5A Low Voltage Current Mode Synchronous PWM Buck
Regulator
Features
■
95% Efficiency, Synchronous Operation
■
Adjustable Output Voltage from 0.8V to V
IN
■
4.5V to 5.5V Input Voltage Range
■
Up to 1.5A Output Current
■
Fixed Frequency 1.3 MHz PWM Operation
■
100% Duty Cycle Low Dropout Operation
■
Soft Start
■
Excellent Load Transient Response
■
3x3mm 6-lead MLP Package
Applications
■
Hard Disk Drive
■
Set Top Box
■
Point of Load Power
■
Notebook Computers
■
Communications Equipment
Description
The FAN2011/FAN2012 is a high-efficiency, low-noise synchro-
nous PWM current mode DC-DC converter, designed for low
voltage applications. It provides up to 1.5A continuous load cur-
rent from the 4.5V to 5.5V input. The output voltage is adjust-
able over a wide range of 0.8V to V
IN
by means of an external
voltage divider.
The FAN2011 is always on, while the FAN2012 has an “Enable
Input,” and the device can be put in the shutdown mode, in
which the ground current falls below 1µA.
A current mode control loop with a fast transient response
ensures excellent line and load regulation. The fixed 1.3MHz
switching frequency enables the user to choose a small, inex-
pensive external inductor and capacitor. Filtering is also easily
accomplished with very small components.
Protection features include input under-voltage lockout, short
circuit protection and thermal shutdown. Soft-start limits in-rush
current during start-up conditions.
The device is available in a 3x3mm 6-lead MLP package, mak-
ing it possible to build a 1.5A complete DC/DC converter in a
tiny space on the PCB.
Typical Application
Figure 1. Typical Application
FAN2011 FAN2012
1
2
3
6
5
4
FB
PGND
SW
PV
IN
V
IN
NC
P1
(A
GND)
L1
R2
R1
+5V
V
OUT
4 x 10µF
3.3µH
10µF
10KΩ
1
2
3
6
5
4
FB
PGND
SW
PV
IN
V
IN
EN
P1
(A
GND)
L1
R2
R1
+5V
V
OUT
4 x 10µF
3.3µH
10µF
10KΩ
