LTC1174
LTC1174-3.3/LTC1174-5
High Efficiency
Step-Down and Inverting
DC/DC Converter
FEATURES
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DESCRIPTIO
High Efficiency: Up to 94%
Peak Inductor Current Independent of
Inductor Value
Short-Circuit Protection
Optimized for 5V to – 5V Applications
Wide V
IN
Range: 4V to 18.5V
Low Dropout Operation
Low-Battery Detector
Pin Selectable Current Limit
Internal 0.9Ω Power Switch: V
IN
= 9V
Only Four External Components Required
130µA Standby Current
Active Low Micropower Shutdown
The LTC
®
1174 is a simple current mode DC/DC converter
ideally suited for 9V to 5V, 5V to 3.3V or 5V to – 5V
operation. With an internal 0.9Ω switch (at a supply
voltage of 9V), the LTC1174 requires only four external
components to construct a complete high efficiency
DC/DC converter.
Under a no load condition the LTC1174 draws only 130µA.
In shutdown, it draws a mere 1µA making this converter
ideal for current sensitive applications. In dropout, the
internal P-channel MOSFET switch is turned on continu-
ously allowing the user to maximize the life of the battery
source.
The maximum inductor current of the LTC1174 family is
pin selectable to either 340mA or 600mA, optimizing
efficiency for a wide range of applications. Operation up to
200kHz permits the use of small surface mount inductors
and capacitors.
For applications requiring higher output current or ultra-
high efficiency, see the LTC1148 data sheet.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
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Distributed Power Systems
Step-Down Converters
Inverting Converters
Memory Backup Supply
Portable Instruments
Battery-Powered Equipment
TYPICAL APPLICATIO
V
IN
9V
3
2
7
High Efficiency Step-Down Converter
100
LTC1174-5 Efficiency
6
V
IN
LB
IN
LB
OUT
I
PGM
LTC1174-5
GND
4
SHUTDOWN
V
OUT
SW
8
1
5
100µH
1N5818
†
+
EFFICIENCY (%)
15µF*
25V
×3
95
V
IN
= 6V
90
85
80
75
L = 100µH
V
OUT
= 5V
I
PGM
= 0V
1
10
LOAD CURRENT (mA)
100 200
1174 TA02
5V
175mA
+
100µF**
10V
1174 TA01
* (3) AVX TPSD156K025
** AVX TPSD107K010
†
COILTRONICS CTX100-4
70
U
V
IN
= 9V
1174fe
U
U
1