LMZ34202 Datasheet, PDF (12/31 Pages) Texas Instruments – SIMPLE SWITCHER 4.5-V to 42-V Input, 2-A Power Module

LMZ34202
SNVSAJ2 – MARCH 2016
7 Detailed Description
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7.1 Overview
The LMZ34202 is a full featured 42-V input, 2-A, synchronous step down converter with PWM, MOSFETs,
inductor, and control circuitry integrated into a low-profile, overmolded package. This device enables small
designs by integrating all but the input and output capacitors, while still leaving the ability to adjust key
parameters to meet specific design requirements. The LMZ34202 provides a 3× output voltage range of 2.5 V to
7.5 V. A single external resistor is used to adjust the output voltage to the desired output. The switching
frequency is also adjustable by using an external resistor or a synchronization pulse to accommodate various
input and output voltage conditions and to optimize efficiency. The device provides accurate voltage regulation
for a variety of loads by using an internal voltage reference that is 2% accurate over temperature. Input under-
voltage lockout is internally set at 3.2 V, but can be adjusted upward using a resistor divider on the INH/UVLO
pin of the device. The INH/UVLO pin can also be pulled low to put the device in standby mode to reduce input
quiescent current. The device provides a power good signal to indicate when the output is within ±5% of its
nominal voltage. Thermal shutdown and current limit features protect the device during an overload condition.
Automatic PFM mode improves light-load efficiency. A 43-pin, QFN, package that includes exposed bottom pads
provides a thermally enhanced solution for space-constrained applications.
7.2 Functional Block Diagram
PWRGD_PU
PWRGD
SENSE+
VERSA COMP
100k2
20k2
OCP
Shutdown
Logic
PWRGD Thermal PVIN
Logic Shutdown UVLO
VADJ
SS/TR
+
+
VREF
Comp
CLK
RT
RTSEL
Oscillator
38.3k2
Power
Stage
and
Control
Logic
LMZ34202
LDO
INH/UVLO
VBSEL
PVIN
PH
10 7H
VOUT
PGND
AGND
12
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