LTM4600EVPBF datasheet(6/24 Pages) LINER

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LTM4600

4600fa

PI FU CTIO S

VIN (Bank 1): Power Input Pins. Apply input voltage

between these pins and GND pins. Recommend placing

input decoupling capacitance directly between VIN pins

and GND pins.

fADJ (Pin A15): A 110k resistor from VIN to this pin sets

the one-shot timer current, thereby setting the switching

frequency. The LTM4600 switching frequency is typically

850kHz. An external resistor to ground can be selected to

reduce the one-shot timer current, thus lower the switching

frequency to accommodate a higher duty cycle step down

requirement. See the applications section.

SVIN(PinA17):SupplyPinforInternalPWMController.Leave

this pin open or add additional decoupling capacitance.

EXTVCC (Pin A19): External 5V supply pin for controller. If

left open or grounded, the internal 5V linear regulator will

power the controller and MOSFET drivers. For high input

voltage applications, connecting this pin to an external

5V will reduce the power loss in the power module. The

EXTVCC voltage should never be higher than VIN.

VOSET (Pin A21): The Negative Input of The Error Ampliﬁer.

Internally, this pin is connected to VOUTwitha100kprecision

resistor. Different output voltages can be programmed with

additional resistors between the VOSET and SGND pins.

COMP (Pin B23): Current Control Threshold and Error

Ampliﬁer Compensation Point. The current comparator

threshold increases with this control voltage. The voltage

ranges from 0V to 2.4V with 0.8V corresponding to zero

sense voltage (zero current).

SGND (Pin D23): Signal Ground Pin. All small-signal

components should connect to this ground, which in turn

connects to PGND at one point.

RUN/SS (Pin F23): Run and Soft-Start Control. Forcing

this pin below 0.8V will shut down the power supply.

Inside the power module, there is a 1000pF capacitor

which provides approximately 0.7ms soft-start time with

200µF output capacitance. Additional soft-start time can

be achieved by adding additional capacitance between the

RUN/SS and SGND pins. The internal short-circuit latchoff

can be disabled by adding a resistor between this pin and

the VIN pin. This pullup resistor must supply a minimum

5µA pull up current.

FCB (Pin G23): Forced Continuous Input. Grounding this

pin enables forced continuous mode operation regardless

of load conditions. Tying this pin above 0.63V enables

discontinuous conduction mode to achieve high efﬁciency

operation at light loads. There is an internal 4.75K resistor

between the FCB and SGND pins.

PGOOD (Pin J23): Output Voltage Power Good Indicator.

When the output voltage is within 10% of the nominal

voltage, the PWRGD is open drain output. Otherwise, this

pin is pulled to ground.

PGND (Bank 2): Power ground pins for both input and

output returns.

VOUT (Bank 3): Power Output Pins. Apply output load

between these pins and GND pins. Recommend placing

High Frequency output decoupling capacitance directly

between these pins and GND pins.

(See Package Description for Pin Assignment)

RUN/SS

FCB

PGOOD

VIN

BANK 1

PGND

BANK 2

VOUT

BANK 3

COMP

SGND

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4600 PN01

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