LTM4677 datasheet(23/116 Pages) AD

23 / 116 page

LTC3883/LTC3883-1

Rev. F

For more information www.analog.com

Figure 3. Load Sharing Connections for 2-Phase Operation

OPERATION

current using the R value stored in the IIN_CAL_GAIN

command. The resulting measured powerstage current

is returned by the READ_IIN command.

The MFR_READ_IIN_CHAN command returns the calcu-

lated powerstage current based on the READ_IOUT value

multiplied by the READ_DUTY_CYCLE value.

The LTC3883 uses an internal 1Ω sense resistor to mea-

sure the VIN pin supply current being consumed by the

LTC3883.ThisvalueisreturnedbytheMFR_READ_ICHIP

command. Refer to the subsection titled Input Current

Sense Amplifier in the Applications Information section

for further detail.

LOAD SHARING

Multiple LTC3883’s can be arrayed in order to provide a

balanced load-share solution by bussing the necessary

pins. Figure 3 illustrates the shared connections required

for load sharing.

The frequency must only be programmed on one of the

LTC3883s. The other(s) must be programmed to External

Clock.

EXTERNAL/INTERNAL TEMPERATURE SENSE

Externaltemperaturecanbebestmeasuredusingaremote

diode-connected PNP transistor such as the MMBT3906.

The emitter should be connected to the TSNS pin while the

base and collector terminals of the PNP transistor should

be returned to the LTC3883’s GND pin, preferably using

a star connection. It is possible to connect the collector

of the PNP to the source of the bottom MOSFET. This may

optimize board layout allowing the PNP closer proximity

to the power FETs. The base of the PNP must still be tied to

ground.Forbestnoiseimmunity,theconnectionsshouldbe

routed differentially and a 10nF capacitor should be placed

100

LTC3883 + POWER STAGE

ITH

VIN

POWER STAGE

IIN_SNS

VIN_SNS

LTC3883 + POWER STAGE

ITH

NOTE: SOME CONNECTORS

AND COMPONENTS OMITTED

FOR CLARITY

ISENSE+

ISENSE–

VSENSE+

VSENSE–

CONTROL

VSUPPLY

SMBALERT

FAULT

PWM CLOCK

SHARE CLOCK

RUN

ALERT

GPIO

SYNC

SHARE_CLK

RUN

ALERT

GPIO

SYNC

SHARE_CLK

ISENSE+

ISENSE–

PGND

GND

PGND

3883 F03

GND

VSENSE+

VSENSE–

LOAD

IIN_SNS

VIN_SNS

VIN

POWER STAGE

LTM4677 Datasheet(PDF) 23 Page - Analog Devices

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