SLVUAF6A June   2015  – May 2021 TPS62745

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Background
  3. 2Setup
    1. 2.1 Input/Output Connector Descriptions
    2. 2.2 Operation
  4. 3Common Efficiency Measurement Errors with Ultra-Low Iq Devices
    1. 3.1 Efficiency Measurement Setup
    2. 3.2 Pullup and Pulldown Resistors
  5. 4Board Layout
  6. 5Schematic and Bill of Materials
    1. 5.1 Schematic
    2. 5.2 Bill of Materials
  7. 6Revision History

Pullup and Pulldown Resistors

In addition to the input capacitor and remote sense lines noted in Section 3.1, any pullup or pulldown resistors can draw significant current and affect the measured efficiency. For example, if the VSEL2 pin were pulled up to the input voltage with a 1-MΩ resistor and the pin were tied low through JP4, this would draw an extra 3.6 µA from the input source at a 3.6-V input voltage. This would greatly affect the efficiency at very light loads. For this reason, no pullup or pulldown resistors have been used on the TPS62745EVM-622. The final application circuit should ensure that all digital inputs to the TPS62745 are terminated either high or low and not left floating, per the device data sheet.