LTC3716
2-Phase, 5-Bit VID,
Current Mode, High Efficiency,
Synchronous Step-Down
Switching Regulator
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FEATURES
DESCRIPTIO
The LTC®3716 is a 2-phase, VID programmable, synchro-
nous step-down switching regulator controller that drives
twoN-channelexternalpowerMOSFETstagesinafixedfre-
quency architecture. The 2-phase controller drives its two
output stages out of phase at frequencies up to 300kHz to
minimize the RMS ripple currents in both input and output
capacitors.The2-phasetechniqueeffectivelymultipliesthe
fundamental frequency by two, improving transient re-
sponse while operating each channel at an optimum fre-
quency for efficiency. Thermal design is also simplified.
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Output Stages Operate Antiphase Reducing Input
and Output Capacitance Requirements and Power
Supply Induced Noise
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Dual Input Supply Capability for Load Sharing
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5-Bit Mobile VID Code: VOUT = 0.6V to 1.75V
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±1% Output Voltage Accuracy
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True Remote Sensing Differential Amplifier
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Power Good Output Voltage Monitor
Supports Active Voltage Positioning
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Current Mode Control Ensures Current Sharing
OPTI-LOOPTM Compensation Minimizes COUT
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An operating mode select pin (FCB) can be used to regu-
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Three Operational Modes: PWM, Burst and Cycle Skip
Programmable Fixed Frequency: 150kHz to 300kHz
Wide VIN Range: 4V to 36V Operation
Adjustable Soft-Start Current Ramping
Internal Current Foldback and Short-Circuit Shutdown
Overvoltage Soft Latch Eliminates Nuisance Trips
late a secondary winding or select among three modes
includingBurstModeTM operationforhighestefficiency.An
internaldifferentialamplifierprovidestrueremotesensing
of the regulated supply’s positive and negative output ter-
minals as required in high current applications.
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The RUN/SS pin provides soft-start and optional timed,
short-circuit shutdown. Current foldback limits MOSFET
dissipation during short-circuit conditions when the
overcurrentlatchoffisdisabled.OPTI-LOOPcompensation
allows the transient response to be optimized for a wide
range of output capacitors and ESR values.
Available in 36-LUead Narrow SSOP Package
APPLICATIO S
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Mobile Computer CPU Supply
, LTC and LT are registered trademarks of Linear Technology Corporation.
OPTI-LOOP and Burst Mode are trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
V
IN
5V TO 28V
10µF
35V
×4
0.1µF
V
IN
FCB
TG1
BOOST1
SW1
S
0.002Ω
2
RUN/SS
1
0.47µF
220pF
1µH
3.3k
S
3
4
LTC3716
D1
I
TH
BG1
SGND
PGND
+
SENSE1
SENSE1
PGOOD
–
5 VID BITS VID0–VID4
TG2
BOOST2
SW2
V
0.002Ω
OUT
1
2
EAIN
0.47µF
0.6V TO 1.75V
40A
1µH
ATTENOUT
ATTENIN
3
4
D2
BG2
+
V
V
V
INTV
DIFFOUT
CC
+
C
OUT
+
–
SENSE2
SENSE2
OS
1000µF
4V
10µF
+
–
OS
×2
3716 F01
Figure 1. High Current Dual Phase Step-Down Converter
1