LTM4614 Ver la hoja de datos (PDF) - Linear Technology
Número de pieza
componentes Descripción
Fabricante
LTM4614 Datasheet PDF : 20 Pages
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LTM4614
Decoupling Requirements TA = 25°C. Use Figure 1 configuration for each channel.
SYMBOL
CIN
COUT
PARAMETER
External Input Capacitor Requirement
(VIN = 2.375V to 5.5V, VOUT = 1.5V)
External Output Capacitor Requirement
(VIN = 2.375V to 5.5V, VOUT = 1.5V)
CONDITIONS
IOUT = 4A
IOUT = 4A
MIN TYP MAX UNITS
22
µF
100
µF
Operation
LTM4614 Power Module Description
The LTM4614 is a standalone dual nonisolated switching
mode DC/DC power supply. It can deliver up to 4A of DC
output current for each channel with few external input
and output capacitors. This module provides two precisely
regulated output voltages programmable via one external
resistor for each channel from 0.8V DC to 5V DC over
a 2.375V to 5.5V input voltage. The typical application
schematic is shown in Figure 12.
The LTM4614 has two integrated constant frequency cur-
rent mode regulators, with built-in power MOSFETs with
fast switching speed. The typical switching frequency is
1.25MHz. With current mode control and internal feedback
loop compensation, these switching regulators have suf-
ficient 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, current limiting is provided in an overcur-
rent condition with thermal shutdown. In addition, inter-
nal overvoltage and undervoltage comparators pull the
open-drain PGOOD outputs low if the particular output
feedback voltage exits a ±7.5% window around the regu-
lation point. Furthermore, in an overvoltage condition,
internal top FET, M1, is turned off and bottom FET, M2,
is turned on and held on until the overvoltage condition
clears, or current limit is exceeded.
Pulling each specific RUN pin below 0.8V forces the spe-
cific regulator controller into its shutdown state, turning
off both M1 and M2 for each power stage. At low load
current, each regulator works in continuous current mode
by default to achieve minimum output voltage ripple.
The TRACK and RUN/SS pins are used for power supply
tracking and soft-start programming for each specific
regulator. See the Applications Information section.
The LTM4614 is internally compensated to be stable over
the operating conditions. Table 4 provides a guideline for
input and output capacitance for several operating con-
ditions. The LTpowerCADâ„¢ GUI is available for transient
and stability analysis.
The FB pins are used to program the specific output volt-
age with a single externally connected resistor to ground.
4614fb
7
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