LMZ12001EXT,LMZ12002EXT,LMZ12003EXT,
LMZ14201EXT,LMZ14202EXT,LMZ14203EXT
Application Note 2084 LMZ1420xEXT / LMZ1200xEXT Evaluation Board
Literature Number: SNVA456
LMZ1420xEXT /
LMZ1200xEXT Evaluation
Board
National Semiconductor
Application Note 2084
Alan Martin
August 16, 2010
Introduction
The LMZ1420xEXT and LMZ1200xEXT SIMPLE SWITCH-
ER® power modules are easy-to-use DC-DC solution capa-
ble 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 package that
enhances thermal performance and allows for hand or ma-
chine soldering.
The LMZ14203EXT/2EXT/1EXT can accept an input voltage
rail between 6V and 42V and the LMZ12003EXT/2EXT/1EXT
can accept an input voltage rail between 4.5V and 20V. The
devices can deliver an adjustable and highly accurate output
voltage as low as 0.8V and as high as 6V. The control struc-
ture is constant on-time with input voltage feed forward. This
creates a nearly constant switching frequency across the in-
put voltage range. The control loop operates well with low
ESR output capacitors such as ceramics. An output feed-for-
ward capacitor across the upper feedback resistor trims for
optimum transient response. The precision enable input al-
lows for programmable UVLO of the input supply. The exter-
nal soft-start capacitor facilitates controlled startup output rise
time. The LMZ1420xEXT and LMZ1200xEXT family is a reli-
able and robust solution with the following features: lossless
cycle-by-cycle valley current limit to protect for over current
or short-circuit fault, thermal shutdown, input under-voltage
lock-out, and will start up into a pre-biased output. The
LMZ1420xEXT and LMZ1200xEXT families are shock and
vibration certified and rated for operation down to –55°C.
Board Specifications
•LMZ1420xEXT VIN = 6V to 42V
•LMZ1420xEXT enable UVLO = 8V
•LMZ1420xEXT VOUT = 3.3V
•LMZ1200xEXT VIN = 4.5V to 20V
•LMZ1200xEXT enable UVLO = 4.5V
•LMZ1200xEXT VOUT = 1.8V
•Operates at full load up to 80°C ambient at 12V input
•θJA = 20°C / W, θJC = 1.9°C / W
•Designed on four layers, all four layers are 1 oz. copper
weight
•The two internal ground planes are identical
•Measures 1.705 in. x 3.03 in. (4.33 cm x 7.7cm) and is
62mil (.062”) thick of FR4 laminate material
For additional circuit modifications refer to the Design Con-
sideration section of the LMZ1420xEXT or LMZ1200xEXT
data sheet. For negative output voltage connections see
AN-2027.
Additional Footprints
Additional component mounting pads are available to exper-
iment with alternative Cin and Cout combinations or a zener
clamp on the enable input. See Figure 6 for corresponding
schematic locations.
30131501
FIGURE 1. Evaluation Board Schematic
(LMZ1200xEXT 1.8V application values shown in parentheses)
© 2010 National Semiconductor Corporation 301315 www.national.com
LMZ1420xEXT / LMZ1200xEXT Evaluation Board AN-2084
TABLE 1. LMZ1420xEXT Bill of Materials, VIN = 8V to 42V, VOUT = 3.3V, IOUT (MAX) = 3A / 2A / 1A
Designator Description Case Size Manufacturer Manufacturer P/N Quantity
U1 SIMPLE SWITCHER® TO-PMOD-7 National
Semiconductor
LMZ14203EXTTZ or
LMZ14202EXTTZ or
LMZ14201EXTTZ
1
CIN4, CO1 1 µF, X7R, 50V 1206 Taiyo Yuden UMK316B7105KL-T 2
CIN2 10 µF, X5R, 50V 1210 Taiyo Yuden UMK325BJ106MM-T 1
CO2 100 µF, X5R, 6.3V 1210 Taiyo Yuden JMK325BJ107MM-T 1
CSS, CFF 0.022 µF, X7R, 100V 0805 AVX 08051C223JAT2A 2
RENB 11.8k 0805 Panasonic ERJ-6ENF1182V 1
RENT 68.1 kΩ0805 Panasonic ERJ-6ENF6812V 1
RFBT 3.32 kΩ0805 Vishay-Dale CRCW08053K32FKEA 1
RFBB 1.07 kΩ0805 Panasonic CRCW080534K8FKEA 1
RON 61.9 kΩ0805 Panasonic ERJ-6ENF6192V 1
TABLE 2. LMZ1200xEXT Bill of Materials, VIN = 4.5 to 20V, VOUT = 1.8V, IOUT (MAX) = 3A / 2A / 1A
Designator Description Case Size Manufacturer Manufacturer P/N Quantity
U1 SIMPLE SWITCHER® TO-PMOD-7 National
Semiconductor
LMZ12003EXTTZ or
LMZ12002EXTTZ or
LMZ12001EXTTZ
1
CIN4, CO1 1 µF, X7R, 50V 1206 Taiyo Yuden UMK316B7105KL-T 2
CIN2 10 µF, X5R, 50V 1210 Taiyo Yuden UMK325BJ106MM-T 1
CO2 100 µF, X5R, 6.3V 1210 Taiyo Yuden JMK325BJ107MM-T 1
CSS, CFF 0.022 µF, X7R, 100V 0805 AVX 08051C223JAT2A 2
RENB 11.8k 0805 Panasonic ERJ-6ENF1182V 1
RENT 32.4KΩ0805 Panasonic ERJ-6ENF3242V 1
RFBT 1.87 kΩ0805 Vishay-Dale CRCW08051K87FKEA` 1
RFBB 1.50 kΩ0805 Panasonic CRCW08051K50FKEA 1
RON 32.4KΩ0805 Panasonic ERJ-6ENF3242V 1
Performance Characteristics
LMZ14203EXT Load and Line Regulation
30131505
LMZ12003EXT Load and Line Regulation
30131504
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AN-2084
LMZ14203EXT Efficiency
30131502
LMZ12003EXT Efficiency
30131503
LMZ14202EXT Efficiency
30131520
LMZ12002EXT Efficiency
30131521
LMZ14201EXT Efficiency
30131522
LMZ12001EXT Efficiency
30131523
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AN-2084
LMZ14203EXT Thermal Derating
30131515
LMZ12003EXT Thermal Derating
30131516
LMZ14202EXT Thermal Derating
30131524
LMZ12002EXT Thermal Derating
30131525
LMZ14201EXT Thermal Derating
30131526
LMZ12001EXT Thermal Derating
30131527
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AN-2084
LMZ14203EXT Current Limit VOUT = 3.3V
30131528
LMZ12003EXT Current Limit VOUT = 1.8V
30131529
LMZ14202EXT Current LimitVOUT = 3.3V
30131530
LMZ12002EXT Current Limit VOUT = 1.8V
30131531
LMZ14201EXT Current Limit VOUT = 3.3V
30131532
LMZ12001EXT Current Limit VOUT = 1.8V
30131533
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AN-2084
LMZ14203EXT Startup VIN = 12V
30131534
LMZ12003EXT Startup VIN = 12V
30131535
LMZ14203EXT Output Ripple VOUT = 3.3V
IOUT = 3A, BW = 200 MHz
30131517
LMZ14203EXT Transient Response VIN = 24V
VOUT = 3.3V, 0.6 A to 3A Step
30131518
PCB Layout Diagrams
Gerber and CAD files can be download from the LMZ14203EXT product folder.
30131509
FIGURE 2. Top Layer
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AN-2084
30131510
FIGURE 3. Internal Layer I (Ground)
Heat Sinking Layer
30131511
FIGURE 4. Internal Layer II (Ground)
Heat Sinking Layer
30131512
FIGURE 5. Bottom Layer (Ground and Routing)
Heat Sinking Layer
7 www.national.com
AN-2084
30131513
FIGURE 6. LMZ14203EXT PCB CAD package schematic
DNS = Component not installed
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AN-2084
Notes
9 www.national.com
AN-2084
Notes
AN-2084 LMZ1420xEXT / LMZ1200xEXT Evaluation Board
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