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

Efficiency Measurement Setup

To accurately measure the efficiency of the TPS62745EVM-622, use the setup described in SLVA236 Figure 6. The 'Additional Input Capacitor' referred to in that application note is not needed as C5 is already included on the TPS62745EVM-622. Any additional input capacitance is not recommended as it incurs increased leakage on the input which lowers the measured efficiency.

When measuring efficiency through the setup in SLVA236, special care must be taken to remove the current consumed by the measurement instruments from the efficiency calculations. Such measurement instruments typically include the input voltage and output voltage multimeters as well as the input power supply's remote sense lines (if it has this capability). The current into these points affects the measured efficiency at very light loads. Two possible methods to overcome this are: measuring the current into these points (measure the current into the multimeters and/or remote sense lines) and then subtracting this current from the efficiency calculation or simply removing these instruments from the test setup. At very light load currents, it is typically best to remove the remote sense lines of the input power supply and then measure the current into the input and output voltage multimeters to get the most accurate efficiency measurement.