LTC3716
2-Phase, 5-Bit VID,
Current Mode, High Efficiency,
Synchronous Step-Down
Switching Regulator
FEATURES
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DESCRIPTIO
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Output Stages Operate Antiphase Reducing Input
and Output Capacitance Requirements and Power
Supply Induced Noise
Dual Input Supply Capability for Load Sharing
5-Bit Mobile VID Code: V
OUT
= 0.6V to 1.75V
±1%
Output Voltage Accuracy
True Remote Sensing Differential Amplifier
Power Good Output Voltage Monitor
Supports Active Voltage Positioning
Current Mode Control Ensures Current Sharing
OPTI-LOOP
TM
Compensation Minimizes C
OUT
Three Operational Modes: PWM, Burst and Cycle Skip
Programmable Fixed Frequency: 150kHz to 300kHz
Wide V
IN
Range: 4V to 36V Operation
Adjustable Soft-Start Current Ramping
Internal Current Foldback and Short-Circuit Shutdown
Overvoltage Soft Latch Eliminates Nuisance Trips
Available in 36-Lead Narrow SSOP Package
The LTC
®
3716 is a 2-phase, VID programmable, synchro-
nous step-down switching regulator controller that drives
two N-channel external power MOSFET stages in a fixed fre-
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. The 2-phase technique effectively multiplies the
fundamental frequency by two, improving transient re-
sponse while operating each channel at an optimum fre-
quency for efficiency. Thermal design is also simplified.
An operating mode select pin (FCB) can be used to regu-
late a secondary winding or select among three modes
including Burst Mode
TM
operation for highest efficiency. An
internal differential amplifier provides true remote sensing
of the regulated supply’s positive and negative output ter-
minals as required in high current applications.
The RUN/SS pin provides 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 compensation
allows the transient response to be optimized for a wide
range of output capacitors and ESR values.
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.
TYPICAL APPLICATIO
0.1µF
220pF
I
TH
SGND
PGOOD
5 VID BITS
FCB
V
IN
TG1
BOOST1
SW1
S
10µF
35V
×4
0.47µF
1µH
S
RUN/SS
3.3k
1
0.002Ω
2
3
4
LTC3716
BG1
PGND
D1
VID0–VID4
EAIN
ATTENOUT
ATTENIN
V
DIFFOUT
V
OS –
V
OS +
SENSE1
+
SENSE1
–
TG2
BOOST2
SW2
BG2
SENSE2
+
SENSE2
–
D2
0.47µF
1µH
3
1
0.002Ω
2
4
V
OUT
0.6V TO 1.75V
40A
Figure 1. High Current Dual Phase Step-Down Converter
+
INTV
CC
10µF
U
V
IN
5V TO 28V
U
U
+
C
OUT
1000µF
4V
×2
3716 F01
1
LINER [ LINEAR TECHNOLOGY ]
