LTC3729L-6 Datasheet, PDF (1/28 Pages) Linear Technology – PolyPhase, Synchronous Step-Down Switching Regulator

LTC3729L-6
PolyPhase, Synchronous
Step-Down Switching Regulator
FEATURES
DESCRIPTIO
s _{Reduces Required Input Capacitance and Power}
Supply Induced Noise
s _{True Remote Sensing Differential Amplifier}
s _{0.6V, ±1% Voltage Reference Accuracy}
s _{PolyPhase Controller Operates from Two to Twelve}
Phases
s _{Current Mode Control Ensures Current Sharing}
s _{Phase-Lockable Fixed Frequency: 250kHz to 550kHz}
s _OPTI-LOOP^® _{Compensation Reduces COUT}
s _{Power Good Output Voltage Monitor}
s _{Wide VIN Range: 4V to 30V Operation}
s _{Very Low Dropout Operation: 99% Duty Cycle}
s _{Adjustable Soft-Start Current Ramping}
s _{Internal Current Foldback Plus Shutdown Timer}
s _{Overvoltage Soft-Latch Eliminates Nuisance Trips}
s _{Micropower Shutdown}
s _{32-Lead 5mm × 5mm Plastic QFN Package}
U
APPLICATIO S
s _{Desktop Computers}
s _{Internet Servers}
s _{Large Memory Arrays}
s _{DC Power Distribution Systems}
, LTC and LT are registered trademarks of Linear Technology Corporation.
OPTI-LOOP is a registered trademark of Linear Technology Corporation.
PolyPhase is a trademark of Linear Technology Corporation.
The LTC^®3729L-6 is a PolyPhase^TM synchronous step_-
down current mode switching regulator controller with a
0.6V reference that drives N-channel external power
MOSFET stages in a phase-lockable fixed frequency archi-
tecture. The PolyPhase controller drives its two output
stages out of phase at frequencies up to 550kHz to
minimize the RMS ripple currents in both input and output
capacitors. The output clock signal allows expansion for
up to 12 evenly phased controllers for systems requiring
15A to 200A of output current. This PolyPhase technique
effectively multiplies the fundamental frequency by the
number of channels used, improving transient response
while operating each channel at an optimum frequency for
efficiency. Thermal design is also simplified.
An internal differential amplifier provides true remote
sensing of the regulated supply’s positive and negative
output terminals as required for high current applications.
A RUN/SS pin provides both soft-start and optional timed,
short-circuit shutdown. Current foldback limits MOSFET
dissipation during short-circuit conditions when the
overcurrent latchoff is disabled. OPTI-LOOP compensa-
tion allows the transient response to be optimized over a
wide range of output capacitance and ESR values. The
LTC3729L-6 includes a power good output pin that
indicates when the output voltage is inside the ±10%
tolerance window.
TYPICAL APPLICATIO
0.1µF
0.1µF
3300pF
1.5k
10k
60.4k
V_IN ^LTC3729L-6 TG1
BOOST1
SW1
RUN/SS
BG1
PGOOD
I_TH
CLKOUT
PGND
SENSE1⁺
SENSE1^–
TG2
SGND
BOOST2
SW2
V_DIFFOUT
EAIN
V_OS–
V_OS+
BG2
INTV_CC
SENSE2⁺
SENSE2^–
10Ω
0.47µF
0.47µF
10µF CER
X5R
10µF ×6
M1
35V
CERAMIC
0.002Ω
L1
M2
1µH
×2
D1
M3
L2
M4
1µH
×2
D2
0.002Ω
C_OUT: T510E108K004AS
D1, D2: SBM540
L1, L2: CEPH149-IROMC-H
M1, M3: Si7840DP
M2, M4: Si7440DP
Figure 1. High Current Dual Phase Step-Down Converter
V_IN
5V TO 15V
V_OUT
0.7V/40A
+ C_OUT
270µF ×4
2V
3729L-6 TA01
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