LTM4662 datasheet(13/34 Pages) LINER

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LTM4662

4662f

For more information www.linear.com/LTM4662

Figure 2. 2-Phase Parallel Configurations

APPLICATIONS INFORMATION

• Tie the RUN pins to the RUN pins of the first module.

• Tie the VFB2 pin to the VFB2 pin of the first module.

Use 1/2 the value for RFB2 and RFB3.

• Tie the VOUTS2– pin to the VOUTS2– pin of the

firstmodule.

• Tie VOUTS2 of both modules together then to the

remote sense output.

• Tie the TRACK/SS2 pin to the TRACK/SS2 pin of the

first module.

See Figure 22 for an example.

Input Capacitors

The LTM4662 module should be connected to a low AC

impedance DC source. For the regulator input, four 10F

input ceramic capacitors are used for RMS ripple current.

A 47F to 100F surface mount aluminum electrolytic bulk

capacitor can be used for more input bulk capacitance.

This bulk input capacitor is only needed if the input

source impedance is compromised by long inductive

leads, traces or not enough source capacitance. If low

impedance power planes are used, then this bulk capaci-

tor is not needed.

For a buck converter, the switching duty-cycle can be

estimated as:

D =

VOUT

VIN

Without considering the inductor current ripple, for each

output, the RMS current of the input capacitor can be

estimated as:

ICIN(RMS) =

IOUT(MAX)

η%

• D • 1− D

(

)

In the above equation, η% is the estimated efficiency of

the power module. The bulk capacitor can be a switcher-

rated aluminum electrolytic capacitor, polymer capacitor.

The LTM4662 is designed for low output voltage ripple

noise and good transient response. The bulk output

capacitors defined as COUT are chosen with low enough

effective series resistance (ESR) to meet the output volt-

age ripple and transient requirements. COUT can be a low

ESR tantalum capacitor, low ESR polymer capacitor or

RUN1

PGOOD1

SW1

VOUT1

VOUTS1

FREQ VIN1 VIN2 CPWR

DRVCC INTVCC

INTVCC

EXTVCC PHASMD

VFB1

VRNG

VOUTS1–

COMP1A

COMP1B

TRACK/SS1

RUN2

PGOOD2

SW2

VOUT2

VOUTS2

VFB2

VOUTS2–

COMP2A

COMP

COMP2B

TRACK/SS2

MODE_PLLIN TEMP1+ TEMP1– SGND GND TEMP2+ TEMP2– CLKOUT

LTM4662

4662 F02

PGOOD2

100µF

×3

RUN

INTVCC

10k

VOUT

1.2V

AT 30A

60.4k

30.1k

REMOTE

SENSED GND

150pF

CHANNEL 2 TEMP MONITOR DIODE

CHANNEL 1 TEMP MONITOR DIODE

INTVCC

100F

×3

115k

10F

25V

×4

4.5V TO 20V

130k

100F

25V

COMP

0.1F

47pF

7.15k

CCOMP

1500pF

470F

2.5V

POSCAP

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