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LT3680_15 Datasheet, PDF (1/24 Pages) Linear Technology – 36V, 3.5A, 2.4MHz Step-Down Switching Regulator with 75A Quiescent Current | |||
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LT3680
36V, 3.5A, 2.4MHz
Step-Down Switching Regulator
with 75µA Quiescent Current
FEATURES
â Wide Input Voltage Range: 3.6V to 36V
â 3.5A Maximum Output Current
â Low Ripple (<15mVP-P) Burst Mode® Operation:
IQ = 75μA at 12VIN to 3.3VOUT
â Adjustable Switching Frequency: 200kHz to 2.4MHz
â Low Shutdown Current: IQ < 0.5μA
â Integrated Boost Diode
â Synchronizable Between 250kHz to 2MHz
â Power Good Flag
â Saturating Switch Design: 95m On-Resistance
â 0.790V Feedback Reference Voltage
â Output Voltage: 0.79V to 30V
â Thermal Protection
â Soft-Start Capability
â Small 10-Pin Thermally Enhanced MSOP and
(3mm à 3mm) DFN Packages
APPLICATIONS
â Automotive Battery Regulation
â Power for Portable Products
â Distributed Supply Regulation
â Industrial Supplies
â Wall Transformer Regulation
DESCRIPTION
The LT®3680 is an adjustable frequency (200kHz to
2.4MHz) monolithic buck switching regulator that accepts
input voltages up to 36V. A high efï¬ciency 95m switch
is included on the die along with a boost Schottky diode
and the necessary oscillator, control, and logic circuitry.
Current mode topology is used for fast transient response
and good loop stability. Low ripple Burst Mode® operation
maintains high efï¬ciency at low output currents while
keeping output ripple below 15mV in a typical application.
In addition, the LT3680 can further enhance low output
current efï¬ciency by drawing bias current from the output
when VOUT is above 3V. Shutdown reduces input supply
current to less than 1μA while a resistor and capacitor on
the RUN/SS pin provide a controlled output voltage ramp
(soft-start). A power good ï¬ag signals when VOUT reaches
91% of the programmed output voltage. The LT3680 is
available in 10-Pin MSOP and 3mm à 3mm DFN packages
with exposed pads for low thermal resistance.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of
Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
5V Step-Down Converter
VIN
6.3V TO 36V
OFF ON
VIN
RUN/SS
BD
BOOST
15k
10μF
680pF
63.4k
VC
LT3680
SW
RT
PG
SYNC
GND
FB
VOUT
5V
3.5A
0.47μF 4.7μH
536k
100k
47μF
3680 TA01a
Efï¬ciency
100
VIN = 12V
90
VIN = 34V
80
VIN = 24V
70
60 VOUT = 5V
L = 4.7μH
f = 600kHz
50
0 0.5 1 1.5 2 2.5
OUTPUT CURRENT (A)
3 3.5
3680 G01
3680fb
1
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