LT3430/LT3430-1
High Voltage, 3A,
200kHz/100kHz Step-Down
Switching Regulators
DESCRIPTION
FEATURES
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Wide Input Range: 5.5V to 60V
3A Peak Switch Current over All Duty Cycles
Constant Switching Frequency:
200kHz (LT3430)
100kHz (LT3430-1)
0.1Ω Switch Resistance
Current Mode
Effective Supply Current: 2.5mA
Shutdown Current: 30µA
1.2V Feedback Reference Voltage
Easily Synchronizable
Cycle-by-Cycle Current Limiting
Small, 16-Pin Thermally Enhanced TSSOP Package
The LT®3430/LT3430-1 are monolithic buck switching
regulators that accept input voltages up to 60V. A high efficiency 3A, 0.1Ω switch is included on the die along with
all the necessary oscillator, control and logic circuitry. A
current mode architecture provides fast transient response
and excellent loop stability.
Special design techniques and a new high voltage process
achieve high efficiency over a wide input range. Efficiency
is maintained over a wide output current range by using
the output to bias the circuitry and by utilizing a supply
boost capacitor to saturate the power switch. Patented
circuitry* maintains peak switch current over the full duty
cycle range. A shutdown pin reduces supply current to
30µA and a SYNC pin can be externally synchronized with
a logic level input from 228kHz to 700kHz for the LT3430
or from 125kHz to 250kHz for the LT3430-1.
APPLICATIONS
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Industrial and Automotive Power Supplies
Portable Computers
Battery Chargers
Distributed Power Systems
The LT3430/LT3430-1 are available in a thermally enhanced
16-pin TSSOP package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
*US Patent # 6498466
TYPICAL APPLICATION
5V, 2A Buck Converter
Efficiency vs Load Current
100
MMSD914TI
VOUT = 5V
VIN = 12V
BOOST
22µH
VIN
4.7µF
100V
30BQ060
LT3430**
+
SHDN
BIAS
SYNC
OFF ON
VOUT
5V
2A
SW
FB
100µF 10V
SOLID
TANTALUM
EFFICIENCY (%)
VIN
5.5V*
TO 60V
90
0.68µF
80
VIN = 42V
70
15.4k
GND
60
LT3430-1 L = 68µH
LT3430 L =27µH
4.99k
VC
50
220pF
3.3k
0
0.5
1.5
2.0
1.0
LOAD CURRENT (A)
2.5
3430 TA02
0.022µF
3430 TA01
*FOR INPUT VOLTAGES BELOW 7.5V, SOME RESTRICTIONS MAY APPLY
** SEE LT3430-1 CIRCUIT IN APPLICATIONS INFORMATION SECTION
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