Datasheet

LTM4603/LTM4603-1
10
4603fb
Power Module Description
The LTM4603 is a standalone nonisolated switching mode
DC/DC power supply. It can deliver up to 6A of DC output
current with few external input and output capacitors.
This module provides precisely regulated output voltage
programmable via one external resistor from 0.6V
DC
to
5.0V
DC
over a 4.5V to 20V wide input voltage. The typical
application schematic is shown in Figure 18.
The LTM4603 has an integrated constant on-time current
mode regulator, ultralow R
DS(ON)
FETs with fast switching
speed and integrated Schottky diodes. The typical switching
frequency is 1MHz at full load. With current mode control
and internal feedback loop compensation, the LTM4603
module has sufficient stability margins and good transient
performance under a wide range of operating conditions
and with a wide range of output capacitors, even all ceramic
output capacitors.
Current mode control provides cycle-by-cycle fast current
limit. Besides, foldback current limiting is provided in an
overcurrent condition while V
FB
drops. Internal overvolt-
age and undervoltage comparators pull the open-drain
PGOOD output low if the output feedback voltage exits a
±10% window around the regulation point. Furthermore,
in an overvoltage condition, internal top FET Q1 is turned
off and bottom FET Q2 is turned on and held on until the
overvoltage condition clears.
Pulling the RUN pin below 1V forces the controller into its
shutdown state, turning off both Q1 and Q2. At low load
current, the module works in continuous current mode by
default to achieve minimum output ripple voltage.
When DRV
CC
pin is connected to INTV
CC
an integrated
5V linear regulator powers the internal gate drivers. If a
5V external bias supply is applied on the DRV
CC
pin, then
an efficiency improvement will occur due to the reduced
power loss in the internal linear regulator. This is especially
true at the high end of the input voltage range.
The LTM4603 has a very accurate differential remote
sense amplifier with very low offset. This provides for
very accurate output voltage measurement at the load.
The MPGM pin, MARG0 pin and MARG1 pin are used to
support voltage margining, where the percentage of margin
is programmed by the MPGM pin, and the MARG0 and
MARG1 select margining.
The PLLIN pin provides frequency synchronization of the
device to an external clock. The TRACK/SS pin is used
for power supply tracking and soft-start programming.
operation