LTM4616
SIMPLIFIED BLOCK DIAGRAM
Table 1. Decoupling Requirements. T
A
= 25°C, Block Diagram Configuration.
SYMBOL
C
IN1
C
IN2
C
OUT1
C
OUT2
PARAMETER
External Input Capacitor Requirement
(V
IN1
= 2.7V to 5.5V, V
OUT1
= 1.5V)
(V
IN2
= 2.7V to 5.5V, V
OUT2
= 2.5V)
External Output Capacitor Requirement
(V
IN1
= 2.7V to 5.5V, V
OUT1
= 1.5V)
(V
IN2
= 2.7V to 5.5V, V
OUT2
= 2.5V)
CONDITIONS
I
OUT1
= 8A
I
OUT2
= 8A
I
OUT1
= 8A
I
OUT2
= 8A
MIN
TYP
22
22
100
100
MAX
UNITS
µF
µF
µF
µF
OPERATION
The LTM4616 is a dual-output standalone nonisolated
switching mode DC/DC power supply. It can provide two
8A outputs with few external input and output capacitors.
This module provides precisely regulated output voltages
programmable via external resistors from 0.6V
DC
to 5V
DC
over 2.7V to 5.5V input voltages. The typical application
schematic is shown in Figure 18.
The LTM4616 has integrated constant frequency current
mode regulators and built-in power MOSFET devices with
fast switching speed. The typical switching frequency is
1.5MHz. For switching noise sensitive applications, it can
be externally synchronized from 0.75MHz to 2.25MHz.
Even spread spectrum switching can be implemented in
the design to reduce noise.
With current mode control and internal feedback loop
compensation, the LTM4616 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 thermal shutdown in an overcurrent condition.
Internal overvoltage and undervoltage comparators pull
the open-drain PGOOD output low if the output feedback
voltage exits a ±10% window around the regulation point.
The power good pins are disabled during margining.
Pulling the RUN pins below 1.3V forces the regulators
into a shutdown state, by turning off both MOSFETs. The
TRACK pin is used for programming the output voltage
ramp and voltage tracking during start-up. See the Ap-
plications Information section.
The LTM4616 is internally compensated to be stable over
all operating conditions. Table 3 provides a guideline
for input and output capacitances for several operating
conditions. LTpowerCAD™ design tool is available for fine
tuning transient and stability perfromance. The FB pin is
used to program the output voltage with a single external
resistor to ground.
Multiphase operation can be easily employed with the
synchronization and phase mode controls. The LTM4616
has clock in and clock out for poly phasing multiple devices
or frequency synchronization.
High efficiency at light loads can be accomplished with
selectable Burst Mode operation using the MODE pin. These
light load features will accommodate battery operation.
Efficiency graphs are provided for light load operation in
the Typical Performance Characteristics section.
Output voltage margining is supported, and can be pro-
gramed from ±5% to ±15% using the MGN and BSEL pins.
4616fe
10
For more information
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