DC1084A-A Linear Technology, DC1084A-A Datasheet - Page 8

• Manufacturer Part Number: DC1084A-A
• Description: LTM4602EV1 UMODULE DEMO BOARD
• Manufacturer: Linear Technology
• Series: µModuler

Specifications of DC1084A-A

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Power - Output: -
• Voltage - Output: 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, 5V
• Current - Output: 6A
• Voltage - Input: 4.5 ~ 20 V
• Regulator Topology: Buck
• Frequency - Switching: 800kHz
• Board Type: Fully Populated
• Utilized Ic / Part: LTM4602
• Lead Free Status / Rohs Status: Not applicable / Not applicable

OPERATION
LTM4602
μModule Description
The LTM4602 is a standalone nonisolated synchronous
switching DC/DC power supply. It can deliver up to 6A of
DC output current with only bulk external input and output
capacitors. This module provides a precisely regulated
output voltage programmable via one external resistor from
0.6V
The input voltage range is 4.5V to 20V. A simplifi ed block
diagram is shown in Figure 1 and the typical application
schematic is shown in Figure 21.
The LTM4602 contains an integrated LTC constant on-time
current-mode regulator, ultralow R
switching speed and integrated Schottky diode. The typical
switching frequency is 850kHz at full load. With current
mode control and internal feedback loop compensation,
the LTM4602 module has suffi cient stability margins and
good transient performance under a wide range of operat-
ing conditions and with a wide range of output capacitors,
even all ceramic output capacitors (X5R or X7R).
Current mode control provides cycle-by-cycle fast current
limit. In addition, foldback current limiting is provided in
an overcurrent condition while V
LTM4602 has defeatable short-circuit latch off. 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. Furthermore,
8
DC
to 5.0V
DC
, not to exceed 80% of the input voltage.
OSET
DS(ON)
drops. Also, the
FETs with fast
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/SS pin low forces the controller into its
shutdown state, turning off both Q1 and Q2. Releasing the
pin allows an internal 1.2μA current source to charge up
the soft-start capacitor. When this voltage reaches 1.5V,
the controller turns on and begins switching.
At low load current the module works in continuous cur-
rent mode by default to achieve minimum output voltage
ripple. It can be programmed to operate in discontinuous
current mode for improved light load effi ciency when the
FCB pin is pulled up above 0.8V and no higher than 6V.
The FCB pin has a 4.75k resistor to ground, so a resistor
to V
When EXTV
linear regulator powers the controller and MOSFET gate
drivers. If a minimum 4.7V external bias supply is ap-
plied on the EXTV
off, and an internal switch connects EXTV
driver voltage. This eliminates the linear regulator power
loss with high input voltage, reducing the thermal stress
on the controller. The maximum voltage on EXTV
6V. The EXTV
V
IN
voltage. Also EXTV
IN
can set the voltage on the FCB pin.
CC
CC
pin is grounded or open, an integrated 5V
voltage should never be higher than the
CC
pin, the internal regulator is turned
CC
must be sequenced after V
CC
to the gate
CC
pin is
IN
4602fa
.