LT1373
250kHz Low Supply Current
High Efficiency
1.5A Switching Regulator
FEATURES
s
s
s
s
s
s
s
s
s
s
s
DESCRIPTIO
1mA I
Q
at 250kHz
Uses Small Inductors: 15µH
All Surface Mount Components
Only 0.6 Square Inch of Board Space
Low Minimum Supply Voltage: 2.7V
Constant Frequency Current Mode
Current Limited Power Switch: 1.5A
Regulates Positive or Negative Outputs
Shutdown Supply Current: 12µA Typ
Easy External Synchronization
8-Pin SO or PDIP Packages
The LT
®
1373 is a low supply current high frequency
current mode switching regulator. It can be operated in all
standard switching configurations including boost, buck,
flyback, forward, inverting and “Cuk.” A 1.5A high effi-
ciency switch is included on the die, along with all oscilla-
tor, control and protection circuitry. All functions of the
LT1373 are integrated into 8-pin SO/PDIP packages.
Compared to the 500kHz LT1372, which draws 4mA of
quiescent current, the LT1373 switches at 250kHz, typi-
cally consumes only 1mA and has higher efficiency. High
frequency switching allows for small inductors to be used.
All surface mount components consume less than 0.6
square inch of board space.
New design techniques increase flexibility and maintain
ease of use. Switching is easily synchronized to an exter-
nal logic level source. A logic low on the shutdown pin
reduces supply current to 12µA. Unique error amplifier
circuitry can regulate positive or negative output voltage
while maintaining simple frequency compensation tech-
niques. Nonlinear error amplifier transconductance re-
duces output overshoot on start-up or overload recovery.
Oscillator frequency shifting protects external compo-
nents during overload conditions.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s
s
s
s
s
Boost Regulators
CCFL Backlight Driver
Laptop Computer Supplies
Multiple Output Flyback Supplies
Inverting Supplies
TYPICAL APPLICATIO
5V
5
OFF
ON 4 S/S
V
IN
5V-to-12V Boost Converter
L1*
22µH
D1
MBRS120T3
R1
215k
1%
V
OUT
†
12V
EFFICIENCY (%)
100
V
IN
= 5V
f = 250kHz
90
V
SW
LT1373
8
80
+
†
+
C1**
22µF
FB
GND
6, 7
V
C
1
2
C4**
22µF
MAX I
OUT
70
C2
0.01µF
R3
5k
R2
24.9k
1%
L1
I
OUT
15µH 0.3A
22µH 0.35A
*SUMIDA CD75-220KC (22µH) OR
COILCRAFT D03316-153 (15µH)
**AVX TPSD226M025R0200
60
50
1
10
100
OUTPUT CURRENT (mA)
1000
LT1373 • TA02
LT1373 • TA01
U
12V Output Efficiency
U
U
1
LINER [ LINEAR TECHNOLOGY ]
