LTC3707 查看數據表（PDF） - Linear Technology
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LTC3707 Datasheet PDF : 32 Pages
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LTC3707
High Efficiency, 2-Phase
Synchronous Step-Down Switching Regulator
FEATURES
s 180° Phased Dual Controllers Reduce Required
Input Capacitance and Power Supply Induced Noise
s OPTI-LOOP® Compensation Minimizes COUT
s ±1.5% Output Voltage Accuracy over Temperature
s Dual N-Channel MOSFET Synchronous Drive
s Power Good Output Voltage Monitor
s DC Programmed Fixed Frequency 150kHz to 300kHz
s Wide VIN Range: 4.5V to 28V Operation
s Very Low Dropout Operation: 99% Duty Cycle
s Adjustable Soft-Start Current Ramping
s Foldback Output Current Limiting
s Latched Short-Circuit Shutdown with Defeat Option
s Output Overvoltage Protection
s Remote Output Voltage Sense
s Low Shutdown IQ: 20µA
s 5V and 3.3V Standby Regulators
s Small 28-Lead Narrow SSOP Package
s Selectable Constant Frequency, Burst Mode®
Operation or PWM Operation
U
APPLICATIO S
s Notebook and Palmtop Computers, PDAs
s Battery Chargers
s Portable Instruments
s Battery-Operated Digital Devices
s DC Power Distribution Systems
DESCRIPTIO
The LTC®3707 is a high performance dual step-down
switching regulator controller that drives N-channel syn-
chronous power MOSFET stages. A constant frequency
current mode architecture allows adjustment of the fre-
quency up to 300kHz. Power loss and noise due to the ESR
of the input capacitors are minimized by operating the two
controller output stages out of phase.
OPTI-LOOP compensation allows the transient response
to be optimized over a wide range of output capacitance and
ESR values. The precision 0.8V reference and power good
output indicator are compatible with future microproces-
sor generations, and a wide 3.5V to 30V input supply range
encompasses all battery chemistries.
A RUN/SS pin for each controller provides both soft-start
and optional timed, short-circuit shutdown. Current
foldback limits MOSFET dissipation during short-circuit
conditions when overcurrent latchoff is disabled. Output
overvoltage protection circuitry latches on the bottom
MOSFET until VOUT returns to normal. The FCB mode pin
can select among Burst Mode operation, constant fre-
quency mode and continuous inductor current mode or
regulate a secondary winding.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
L1
6.3µH
D1
VOUT1
5V
5A
RSENSE1
0.01Ω
+
COUT1
47µF
6V
SP
R2
105k
1%
M1
M2
R1
20k
1%
+
4.7µF
CB1, 0.1µF
1000pF
CC1
220pF
RC1
15k
D3
VIN
TG1
INTVCC
TG2
BOOST1
BOOST2
SW1
SW2
LTC3707
BG1
BG2
SGND
SENSE1+
PGND
SENSE2+
SENSE1–
VOSENSE1
ITH1
RUN/SS1
CSS1
0.1µF
SENSE2–
VOSENSE2
ITH2
RUN/SS2
CSS2
0.1µF
1µF
D4
CERAMIC
M3
CB2, 0.1µF
M4
1000pF
CC2
220pF
R3
RC2
15k
20k
1%
VIN
CIN 5.2V TO 28V
22µF
50V
CERAMIC
L2
6.3µH
D2
RSENSE2
0.01Ω
R4
63.4k
1%
COUT
56µF
6V
SP
VOUT2
3.3V
5A
M1, M2, M3, M4: FDS6680A
3707 F01
Figure 1. High Efficiency Dual 5V/3.3V Step-Down Converter
3707f
1
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