LTM4630 Просмотр технического описания (PDF) - Linear Technology

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LTM4630

Dual 18A or Single 36A DC/DC µModule Regulator

Linear Technology 

LTM4630

OPERATION

Power Module Description

The LTM4630 is a dual-output standalone nonisolated

switching mode DC/DC power supply. It can provide two

18A outputs with few external input and output capacitors

and setup components. This module provides precisely

regulated output voltages programmable via external

resistors from 0.6VDC to 1.8VDC over 4.5V to 15V input

voltages. The typical application schematic is shown in

Figure 23.

The LTM4630 has dual integrated constant-frequency cur-

rent mode regulators and built-in power MOSFET devices

with fast switching speed. The typical switching frequency

is 500kHz. For switching-noise sensitive applications, it

can be externally synchronized from 400kHz to 780kHz. A

resistor can be used to program a free run frequency on

the FSET pin. See the Applications Information section.

With current mode control and internal feedback loop

compensation, the LTM4630 module has sufficient stabil-

ity margins and good transient performance with a wide

range of output capacitors, even with all ceramic output

capacitors.

Current mode control provides cycle-by-cycle fast current

limit and foldback current limit in an overcurrent condition.

Internal overvoltage and undervoltage comparators pull

the open-drain PGOOD outputs low if the output feedback

voltage exits a ±10% window around the regulation point.

As the output voltage exceeds 10% above regulation, the

bottom MOSFET will turn on to clamp the output voltage.

The top MOSFET will be turned off. This overvoltage protect

is feedback voltage referred.

Pulling the RUN pins below 1.1V forces the regulators

into a shutdown state, by turning off both MOSFETs.

The TRACK pins are used for programming the output

voltage ramp and voltage tracking during start-up or

used for soft-starting the regulator. See the Applications

Information section.

The LTM4630 is internally compensated to be stable over all

operating conditions. Table 4 provides a guide line for input

and output capacitances for several operating conditions.

The Linear Technology µModule Power Design Tool will be

provided for transient and stability analysis. The VFB pin is

used to program the output voltage with a single external

resistor to ground. A differential remote sense amplifier is

available for sensing the output voltage accurately on one

of the outputs at the load point, or in parallel operation

sensing the output voltage at the load point.

Multiphase operation can be easily employed with the

MODE_PLLIN, PHASMD, and CLKOUT pins. Up to 12

phases can be cascaded to run simultaneously with re-

spect to each other by programming the PHASMD pin to

different levels. See the Applications Information section.

High efficiency at light loads can be accomplished with

selectable Burst Mode operation or pulse-skipping opera-

tion using the MODE_PLLIN pin. These light load features

will accommodate battery operation. Efficiency graphs are

provided for light load operation in the Typical Performance

Characteristics section. See the Applications Information

section for details.

A general purpose temperature diode is included inside

the module to monitor the temperature of the module. See

the Applications Information section for details.

The switch pins are available for functional operation

monitoring and a resistor-capacitor snubber circuit can

be careful placed on the switch pin to ground to dampen

any high frequency ringing on the transition edges. See

the Applications Information section for details.

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For more information www.linear.com/LTM4630

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