LTC3736_15 Datasheet, PDF(7/28 Page) Linear Technology – Dual 2-Phase, No RSENSE, Synchronous Controller with Output Tracking

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LTC3736_15 Datasheet, PDF (7/28 Pages) Linear Technology – Dual 2-Phase, No RSENSE, Synchronous Controller with Output Tracking

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LTC3736

PI FU CTIO S (UF/GN Package)

For auxiliary winding applications, connect to a resistor

divider from the auxiliary output. To synchronize with an

external clock using the PLL, apply a CMOS compatible

clock with a frequency between 250kHz and 850kHz. To

select Burst Mode operation at light loads, tie this pin to VIN.

Grounding this pin selects forced continuous operation,

which allows the inductor current to reverse. When

synchronized to an external clock, pulse-skipping operation

is enabled at light loads.

BG1/BG2 (Pins 19, 13/Pins 22, 16): Bottom (NMOS) Gate

Drive Output. These pins drive the gates of the external N-

channel MOSFETs. These pins have an output swing from

PGND to SENSE+.

SENSE1+/SENSE2+ (Pins 21, 11/Pins 24, 14): Positive

Input to Differential Current Comparator. Also powers the

gate drivers. Normally connected to the source of the ex-

ternal P-channel MOSFET.

SW1/SW2 (Pins 22, 10/Pins 1, 13): Switch Node Connec-

tion to Inductor. Also the negative input to differential peak

current comparator and an input to the reverse current

comparator. Normally connected to the drain of the exter-

nal P-channel MOSFETs, the drain of the external N-channel

MOSFET and the inductor.

IPRG1/IPRG2 (Pins 23, 2/Pins 2, 5): Three-State Pins to

Select Maximum Peak Sense Voltage Threshold. These pins

select the maximum allowed voltage drop between the

SENSE+ and SW pins (i.e., the maximum allowed drop

across the external P-channel MOSFET) for each channel.

Tie to VIN, GND or float to select 204mV, 85mV or 125mV

respectively.

VFB1/VFB2 (Pins 24, 7/Pins 3, 10): Feedback Pins. Receives

the remotely sensed feedback voltage for its controller from

an external resistor divider across the output.

FU CTIO AL DIAGRA (Common Circuitry)

RVIN

VIN

(TO CONTROLLER 1, 2)

VIN

CVIN

UNDERVOLTAGE

LOCKOUT

VOLTAGE

REFERENCE

0.6V

VREF

0.7ÂµA

RUN/SS

SHDN

EXTSS

tSEC = 1ms

SYNC/FCB

BURST DEFEAT/

SYNC DETECT

BURSTDIS

PHASE

DETECTOR

INTSS

PLLLPF

VOLTAGE

CONTROLLED

OSCILLATOR

CLK1

CLK2

0.6V

IPRG1

IPRG2

FCB

SECONOMSVSNSCAOETEIXLLRLVITLEMOOAACLLUGTTLTMEOEARDGE

IPROG1

IPROG2

SLOPE

COMP

VFB1

0.54V

VFB2

SLOPE1

SLOPE2

UV1

OV1

SHDN

UV2

OV2

PGOOD

3736 FD

3736fa

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