LTM8027
block DiagraM
V
V
OUT
6.8µH
4.7pF
IN
499k
2.2µF
RUN
SS
AUX
INTERNAL
CURRENT
MODE
CONTROLLER
CONNECTION
TO V
OUT
SYNC
BIAS1
BIAS2
INTERNAL
LINEAR
REGULATOR
INTV
CC
V
IN
GND
R
T
ADJ
8027 BD
operaTion
The LTM8027 is a standalone nonisolated step-down
switching DC/DC power supply with an input voltage
range of 4.5V to 60V that can deliver up to 4A of output
current.Thismoduleprovidesapreciselyregulatedoutput
voltage up to 24V, programmable via one external resistor.
Given that the LTM8027 is a step-down converter, make
sure that the input voltage is high enough to support the
desiredoutputvoltageandloadcurrent. Asimplifiedblock
diagram is given above. The LTM8027 contains a current
mode controller, power switching element, power induc-
tor, power MOSFETs and a modest amount of input and
output capacitance.
The LTM8027 is a fixed frequency PWM regulator. The
switching frequency is set by simply connecting the ap-
propriate resistor from the RT pin to GND.
A linear regulator provides internal power (shown as
INTV on the Block Diagram) to the control circuitry.
CC
The bias regulator normally draws power from the V
IN
pin, but if the BIAS1 pin is connected to an external volt-
age higher than 8.5V, bias power will be drawn from the
external source (typically the regulated output voltage).
This improves efficiency. The RUN pin is used to enable
or place the LTM8027 in shutdown, disconnecting the
output and reducing the input current to less than 9µA.
8027fb
10
Linear [ Linear ]
