SNVU787A July   2021  – September 2022 LMR38010 , LMR38020

 

  1.   LMR38020 LMR38020-Q1 EVM User Guide
  2.   Trademarks
  3. 1General TI High Voltage Evaluation User Safety Guidelines
  4. 2 LMR38020 Evaluation Module
    1. 2.1 Quick Start Procedure
    2. 2.2 Detailed Descriptions
  5. 3Schematic
  6. 4PCB Layout
  7. 5Bill of Materials
  8. 6Revision History

2.2 Detailed Descriptions

This section describes the connectors and the test points on the EVM and how to properly connect, set up, and use the LMR38020EVM. See Figure 2-1 for a top view of the EVM.

    VOUT (J2)Output voltage of the converterVOUT connector and test point connected to the power inductor and the output capacitors. Connect the loading device between VOUT and GND connectors to provide loading to the regulator. Connect the loading device to the board with short wires to handle the DC output current.
    GNDGround of the converterGND is connected to the LMR38020 GND as well as the return terminals of the input and output capacitors. GND is the current return path for both supply voltage and load. Connect to supply and load grounds with short wires.
    VIN (J3)Input voltage to the converterVIN connector and test point connects to the input capacitors and the VIN pin of the LMR38020. Connect the supply voltage from a power supply or a battery between the VIN and GND connectors. The voltage range must be higher than 4.2 V for the device to be active. VVIN higher than 6 V provides a regulated 5-V output voltage. To avoid damaging the device, VVIN must be no greater than 80 V. The current limit on the supply must be high enough to provide the needed supply current when the output is fully loaded. The supply voltage must be connected to the board with short wires.
    VIN_EMIInput voltage to input filter of the converterIf an input filter is desired between the supply voltage and the LMR38020, connect the supply voltage between VIN_EMI and GND on the bottom layer. The supply voltage must be connected to the board with short wires.

    The EMI filter components were not assembled on this evaluation board.

    VIN_S(TP1)Measure VIN voltageIt provides a direct connection to the input capacitor C10 to sense the input voltage. Do not apply input voltage on this test pin.
    EN (J4)Set EN pin optionsUse this jumper to enable, disable the LMR38020. PIN-1 is connected to GND and PIN-2 is connected to EN.
    1. Connect PIN-1 to PIN-2 to disable the device.
    2. Leave PIN-1 and PIN-2 open for EN to be connected to VIN through a resistor divider.
    The system UVLO voltage can be programmed by resistor divider on EN pin. The lower UVLO resistor, R7, was not assembled on this board, so the EN/UVLO voltage pulls up to the input voltage.

    Calculate the lower UVLO resistor, R7, based on the desired turn-on voltage and the upper UVLO resistor, R5, of 115 KΩ. Refer to the External UVLO section of the LMR38020 SIMPLE SWITCHER® 4.2-V to 80-V, 2-A Synchronous Buck Converter Data Sheet for more detailed application information.

    PWRGD (J1)Power-good indication

    PWRGD jumper with PIN-1 connected to PGOOD and PIN-2 connected to the pullup voltage. PIN-1 can be used as a test point to monitor the power-good indicator. This flag indicates whether the output voltage has reached its regulation level. The LMR38020 PGOOD is an open-drain output that is tied to voltage below 20 V through pullup resistor R10.

    Header (J6)Measure VOUT and loop responseJ6 PIN-2 (VO_S) is connected to the output for output voltage sensing and efficiency measurement. PIN-1 (Vinj) is connected to the noise injection resistor R3. The loop response can be measured on J6.