Datasheet

LTM4627
10
4627fc
For more information www.linear.com/LTM4627
Power Module Description
The LTM4627 is a high performance single output stand-
alone nonisolated switching mode DC/DC power supply.
It can provide a 15A output with few external input and
out
put c
apacitors. This module provides precisely regulated
output voltages programmable via external resistors from
0.6V
DC
to 5V
DC
over a 4.5V to 20V input range. The typical
application schematic is shown in Figure 18.
The LTM4627 has an integrated constant-frequency cur
-
rent mode regulator, power MOSFETs, 0.47µH inductor,
and other supporting discrete components. The switch-
ing frequency range is from 400kHz to 770kHz, and the
ty
pic
al operating frequency is 500kHz. For switching
noise-sensitive applications, it can be externally syn
-
chronized from 250kHz to 800kHz, subject to minimum
on-time limitations. A single resistor is used to program
the frequency. See the Applications Information section.
With current mode control and internal feedback loop
compensation, the LTM4627 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 in an overcurrent condition. An internal overvoltage
monitor protects the output voltage in the event of an
OPERATION
overvoltage >10%. The top MOSFET is turned off and the
bottom MOSFET is turned on until the output is cleared.
Pulling the RUN pin below 1.1V forces the regulator into a
shutdown state. The TRACK/SS pin is used for program
-
ming the output voltage ramp and voltage tracking during
start-up. See the Application Information section.
The LTM4627 is internally compensated to be stable over
all operating conditions. T
able 4 provides a guideline for
input and output capacitances for several operating condi
-
tions. LTpowerCAD™ is available for transient and stability
analysis. The V
FB
pin is used to program the output voltage
with a single external resistor to ground.
A remote sense amplifier is provided for accurately sensing
output voltages ≤3.3V at the load point.
Multiphase operation can be easily employed with the
synchronization inputs using an external clock source.
See application examples.
High efficiency at light loads can be accomplished with
selectable Burst Mode operation using the MODE_PLLIN
pin. These light load features will accommodate battery
operation. Efficiency graphs are provided for light load op
-
eration in the Typical Performance Characteristics section.