LTM4671 datasheet(14/36 Pages) AD

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LTM4671

Rev. B

For more information www.analog.com

OPERATION

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

CIN

External Input Capacitor Requirement

(VIN = 3.1V to 20V, VOUT = 1.5V)

µF

COUT0, COUT3 External Output Capacitor Requirement

(VIN = 3.1V to 20V, VOUT = 1.5V)

IOUT = 12A

100

200

µF

COUT1, COUT2 External Output Capacitor Requirement

(VIN = 3.1V to 20V, VOUT = 1.5V)

IOUT = 5A

µF

DECOUPLING REQUIREMENTS

The LTM4671 is a quad output standalone non-isolated

switch mode DC/DC power supply. It has built-in four

separate regulator channels which can deliver 12A, 12A,

5A, 5A continuous output current with few external input

and output capacitors. Two 12A regulator provides pre-

cisely regulated output voltage programmable from 0.6V

to 3.3V via a single external resistor over 3.1V to 20V

input voltage range while the other two 5A regulator can

support output voltage from 0.6V to 5.5V. Dual true dif-

ferentialremotesensingamplifiersareincludedinthehigh

current channels to get accurate regulation at load point.

The typical application schematic is shown in Figure 30.

The LTM4671 has integrated four separate constant on-

time valley current mode regulators, power MOSFETs,

inductors, and other supporting discrete components.

For switching noise-sensitive applications, the switching

frequency can be adjusted by external resistors and the

µModule can be externally synchronized to a clock. See

the Applications Information section.

With current mode control and internal feedback loop

compensation, the LTM4671 module has sufficient stabil-

ity margins and good transient performance with a wide

range of output capacitors, even with all ceramic output

capacitors. For Dual 12A output rails, an optional Type II

C-R-C external compensation network is allowed to cus-

tomize the stability and transient performance.

Current mode control provides the flexibility of paralleling

any of the separate regulator channels with accurate cur-

rent sharing. With a build in clock interleaving between

each two regulator channels, the LTM4671 could easily

employ a 2+1+1 or 2+2 channels parallel operation which

is more than flexible in a multirail POL application like

FPGA.Furthermore,theLTM4671hasCLKINandCLKOUT

pins for frequency synchronization or PolyPhase multiple

devices which allow up to 8 phases of 12A or 5A channels

can be cascaded to run simultaneously.

Currentmodecontrolalsoprovidescycle-by-cyclefastcur-

rent monitoring. An internal overvoltage and undervoltage

comparators pull the open-drain PGOOD output low if the

output feedback voltage exits a ±10% window around the

regulationpoint.Furthermore,inanovervoltagecondition,

internal top FET is turned off and bottom FET is turned on

and held on until the overvoltage condition clears.

Pulling the RUN pin below 0.6V forces the controller into

its shutdown state, turning off both power MOSFETs and

most of the internal control circuitry. At light load currents,

Burst Mode operation can be enabled to achieve higher

efficiency compared to continuous mode for the dual 5A

channels by setting MODE/PLLIN pin floating or tying

to INTVCC. The TRACK/SS pin is used for power supply

trackingandsoft-startprogramming.SeetheApplications

Information section.

Three different temperature sensing pins are included in-

side the module to monitor the temperature of the module

for different channels. See the Applications Information

section for details.

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