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LMZ1420xEXT / LMZ1200xEXT Evaluation Board LMZ1420xEXT / LMZ1200xEXT Evaluation Board Introduction The LMZ1420xEXT and LMZ1200xEXT SIMPLE SWITCHER® power modules are easy-to-use DC-DC solution 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 package that enhances thermal performance and allows for hand or machine 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 structure is constant on-time with input voltage feed forward. This creates a nearly constant switching frequency across the input voltage range. The control loop operates well with low ESR output capacitors such as ceramics. An output feed-forward capacitor across the upper feedback resistor trims for optimum transient response. The precision enable input allows for programmable UVLO of the input supply. The external soft-start capacitor facilitates controlled startup output rise time. The LMZ1420xEXT and LMZ1200xEXT family is a reliable 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. National Semiconductor Application Note 2084 Alan Martin August 16, 2010 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 Consideration 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 experiment with alternative Cin and Cout combinations or a zener clamp on the enable input. See Figure 6 for corresponding schematic locations. AN-2084 30131501 FIGURE 1. Evaluation Board Schematic (LMZ1200xEXT 1.8V application values shown in parentheses) © 2010 National Semiconductor Corporation 301315 www.national.com AN-2084 TABLE 1. LMZ1420xEXT Bill of Materials, VIN = 8V to 42V, VOUT = 3.3V, IOUT (MAX) = 3A / 2A / 1A Designator U1 Description SIMPLE SWITCHER® Case Size TO-PMOD-7 Manufacturer National Semiconductor Taiyo Yuden Taiyo Yuden Taiyo Yuden AVX Panasonic Panasonic Vishay-Dale Panasonic Panasonic Manufacturer P/N LMZ14203EXTTZ or LMZ14202EXTTZ or LMZ14201EXTTZ UMK316B7105KL-T UMK325BJ106MM-T JMK325BJ107MM-T 08051C223JAT2A ERJ-6ENF1182V ERJ-6ENF6812V CRCW08053K32FKEA CRCW080534K8FKEA ERJ-6ENF6192V Quantity 1 CIN4, CO1 CIN2 CO2 CSS, CFF RENB RENT RFBT RFBB RON 1 µF, X7R, 50V 10 µF, X5R, 50V 100 µF, X5R, 6.3V 0.022 µF, X7R, 100V 11.8k 68.1 kΩ 3.32 kΩ 1.07 kΩ 61.9 kΩ 1206 1210 1210 0805 0805 0805 0805 0805 0805 2 1 1 2 1 1 1 1 1 TABLE 2. LMZ1200xEXT Bill of Materials, VIN = 4.5 to 20V, VOUT = 1.8V, IOUT (MAX) = 3A / 2A / 1A Designator U1 Description SIMPLE SWITCHER® Case Size TO-PMOD-7 Manufacturer National Semiconductor Taiyo Yuden Taiyo Yuden Taiyo Yuden AVX Panasonic Panasonic Vishay-Dale Panasonic Panasonic Manufacturer P/N LMZ12003EXTTZ or LMZ12002EXTTZ or LMZ12001EXTTZ UMK316B7105KL-T UMK325BJ106MM-T JMK325BJ107MM-T 08051C223JAT2A ERJ-6ENF1182V ERJ-6ENF3242V CRCW08051K87FKEA` CRCW08051K50FKEA ERJ-6ENF3242V Quantity 1 CIN4, CO1 CIN2 CO2 CSS, CFF RENB RENT RFBT RFBB RON 1 µF, X7R, 50V 10 µF, X5R, 50V 100 µF, X5R, 6.3V 0.022 µF, X7R, 100V 11.8k 32.4KΩ 1.87 kΩ 1.50 kΩ 32.4KΩ 1206 1210 1210 0805 0805 0805 0805 0805 0805 2 1 1 2 1 1 1 1 1 Performance Characteristics LMZ14203EXT Load and Line Regulation LMZ12003EXT Load and Line Regulation 30131504 30131505 www.national.com 2 AN-2084 LMZ14203EXT Efficiency LMZ12003EXT Efficiency 30131502 30131503 LMZ14202EXT Efficiency LMZ12002EXT Efficiency 30131520 30131521 LMZ14201EXT Efficiency LMZ12001EXT Efficiency 30131522 30131523 3 www.national.com AN-2084 LMZ14203EXT Thermal Derating LMZ12003EXT Thermal Derating 30131515 30131516 LMZ14202EXT Thermal Derating LMZ12002EXT Thermal Derating 30131524 30131525 LMZ14201EXT Thermal Derating LMZ12001EXT Thermal Derating 30131526 30131527 www.national.com 4 AN-2084 LMZ14203EXT Current Limit VOUT = 3.3V LMZ12003EXT Current Limit VOUT = 1.8V 30131528 30131529 LMZ14202EXT Current LimitVOUT = 3.3V LMZ12002EXT Current Limit VOUT = 1.8V 30131530 30131531 LMZ14201EXT Current Limit VOUT = 3.3V LMZ12001EXT Current Limit VOUT = 1.8V 30131532 30131533 5 www.national.com AN-2084 LMZ14203EXT Startup VIN = 12V LMZ12003EXT Startup VIN = 12V 30131534 30131535 LMZ14203EXT Output Ripple VOUT = 3.3V IOUT = 3A, BW = 200 MHz LMZ14203EXT Transient Response VIN = 24V VOUT = 3.3V, 0.6 A to 3A Step 30131517 30131518 PCB Layout Diagrams Gerber and CAD files can be download from the LMZ14203EXT product folder. 30131509 FIGURE 2. Top Layer www.national.com 6 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. 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