LMZ14203H Datasheet, PDF (1/10 Pages) National Semiconductor (TI) – Evaluation Board modules for high output voltage are easy-to-use DC-DC

LMZ14203H/02H/01H
Evaluation Board
National Semiconductor
Application Note 2089
Denislav D. Petkov
January 7, 2011
Introduction
The LMZ14203H/02H/01H SIMPLE SWITCHER® power
modules for high output voltage are easy-to-use DC-DC so-
lutions capable of driving up to a 3A load with exceptional
power conversion efficiency, output voltage accuracy, line
and load regulation. They are available in an innovative pack-
age that enhances thermal performance and allows for hand
or machine soldering.
The LMZ14203H/02H/01H Evaluation Board is configured for
12V output voltage from 15V to 42V input. The precision en-
able input allows for programmable UVLO of the input supply.
The resistor voltage divider R_ENT and R_ENB set the input UVLO
threshold. Connect the V_IN turret terminal to the EN turret on
the board to enable operation.
The external soft-start capacitor C_SS facilitates controlled
startup output rise time. The resistors R_FBT and R_FBB set the
output voltage. An output feed-forward capacitor C_FF across
the upper feedback resistor trims for optimum transient re-
sponse. The control loop operates well with low ESR output
capacitors such as ceramic and polymer electrolytic capaci-
tors. The resistor R_ON sets the operating frequency. See
datasheet for component selection details.
The LMZ14203H/02H/01H PCB layout offers excellent ther-
mal performance, achieving junction-to-ambient thermal re-
sistance θ_JA of 14.9°C/W. The evaluation board with its
default Bill of Materials offers great EMI performance, com-
plying with the EN 55022 Class B radiated emissions stan-
dard. The solution also complies with the CISPR22 conducted
emissions standard with the addition of a small input filter.
Board Specifications
• V_IN = 15V to 42V
• V_OUT = 12V
• 3A max load at 24V_IN and 65°C T_AMB
• Low radiated EMI (EN 55022 Class B compliant)
• 400kHz switching frequency
• Enable UVLO set at 13.5V
• θ_JA = 14.9°C/W
• 4 copper layers
• 2 oz copper on top and bottom layer
• 1 oz copper on internal layers
• 6.985 cm x 7.620 cm (2.75 in x 3 in) with 1.575 cm (.062
in) thickness of FR4 laminate material
Additional Footprints
Additional component mounting pads are available to exper-
iment with alternative input and output capacitor combina-
tions or a zener clamp on the enable input. See Figure 6 for
corresponding schematic locations.
FIGURE 1. Evaluation Board Schematic
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