LTM4608_1 Datasheet, PDF (9/26 Pages) Linear Technology – Low VIN, 8A DC/DC Module Regulator with Tracking, Margining, and Frequency Synchronization

SIMPLIFIED BLOCK DIAGRAM
LTM4608
SV_IN
TRACK
MGN
BSEL
PGOOD
MODE
RUN
CLKIN
CLKOUT
PHMODE
I_TH
PLLLPF
I_THM
SGND
INTERNAL
COMP
INTERNAL
FILTER
INTERNAL
FILTER
POWER
CONTROL
V_IN
+
V_IN
2.7 TO 5.5V
10µF
10µF
10µF
C_IN
M1
0.22µH
M2
22µF
SW
V_OUT
V_OUT
1.5V
8A
22pF
C_OUT
GND
10k
FB
R_FB
6.65k
4608 BD
Figure 1. Simplified LTM4608 Block Diagram
Table 1. Decoupling Requirements. T_A = 25°C, Block Diagram Configuration.
SYMBOL
PARAMETER
CONDITIONS
C_IN
External Input Capacitor Requirement I_OUT = 8A
(V_IN = 2.7V to 5.5V, V_OUT = 1.5V)
C_OUT
External Output Capacitor Requirement I_OUT = 8A
(V_IN = 2.7V to 5.5V, V_OUT = 1.5V)
MIN TYP MAX UNITS
10
µF
100
µF
OPERATION
The LTM4608 is a standalone nonisolated switch mode
DC/DC power supply. It can deliver up to 8A of DC output
current with few external input and output capacitors.
This module provides precisely regulated output voltage
programmable via one external resistor from 0.6V DC to
5.0V DC over a 2.7V to 5.5V input voltage. The typical
application schematic is shown in Figure 18.
The LTM4608 has an integrated constant frequency current
mode regulator 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 LTM4608 module has sufficient stabil-
ity margins and good transient performance with a wide
range of output capacitors, even with all ceramic output
capacitors.
4608fc
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