LTM8049 datasheet(7/20 Pages) LINER

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LTM4661

4661f

For more information www.linear.com/LTM4661

BLOCK DIAGRAM

INTVCC

SYNC/MODE

SDB

COMP

FREQ

VIN

VOUT

VIN

3.3V

VOUT

5V/2A

4661 BD

2.2µF

4.7µF

2.2µF

22µF

47µF

28k

31.6k

100k

GND

VOUT

INTERNAL

COMP

POWER CONTROL

2.2µH

VIN

OPERATION

The LTM4661 is a dual-phase single-output standalone

non-isolatedstep-upswitchingmodeDC/DCpowersupply.

This module provides a precisely regulated output voltage

programmable via one external resistor from 1.2V to 15V

and provides up to 4A switch current (see Table 1) with

few external input and output ceramic capacitors. It also

offers the unique ability to start up from inputs as low as

1.8V and continue to operate from inputs as low as 0.7V

for output voltages greater than 2.5V. The typical applica-

tion schematic is shown in Figure 17.

The LTM4661 contains an integrated fixed frequency, cur-

rent mode regulator, power MOSFETs, inductor and other

supporting discrete components. The default switching

frequency is 1MHz. For switching noise-sensitive applica-

tions, the switching frequency can be adjusted by external

resistors and the µModule regulator can be externally

synchronized to a clock at least 100ns minimum.

With current mode control and internal feedback loop

compensation, the LTM4661 module has sufficient stabil-

ity margins and good transient performance with a wide

range of output capacitors, even with all ceramic output

capacitors.

Pulling the SDB pin above 1.6V enables module opera-

tion and forcing it below 0.25V shuts the module off with

quiescent current below 1µA. At light load currents, Burst

Modeoperationcanbeenabledtoachievehigherefficiency

comparedtocontinuousmode(CCM)bysettingtheSYNC/

MODEpintoGND.Aninternal10mssoft-startlimitsinrush

current during start-up and simplifies the design process

while minimizing the number of external components.

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