SLUU180B January   2022  – February 2022 TPS40070 , TPS40071

 

  1.   Trademarks
  2. 1Introduction
  3. 2Description
  4. 3Schematic
    1. 3.1 Output Filter Components
    2. 3.2 MOSFET Selection
    3. 3.3 Frequency Feedforward Resistor Selection
    4. 3.4 Output Voltage Setpoint
    5. 3.5 Short Circuit Protection Resistor Selection
    6. 3.6 Miscellaneous Parts
    7. 3.7 Control Loop Compensation
  5. 4Test Setup
  6. 5Results
    1. 5.1 Control Loop Characteristics
  7. 6Assembly Drawing and PCB Layout
  8. 7List of Materials
  9. 8Reference
  10. 9Revision History

5 Results

Figure 5-1 through Figure 5-3 show the efficiency of the TPS40071EVM−001 with VOUT = 1.2 V, 1.8 V, and 3.3 V in Figure 5-1, Figure 5-2, and Figure 5-3, respectively. The converter is seen to perform very efficiently throughout the operating range. With VIN = 5 V, the gate drive is reduced and the efficiency can be seen to decrease more rapidly as load current increases.

Figure 5-1 Efficiency vs Output Current (VOUT = 1.2 V)
Figure 5-2 Efficiency vs Output Current (VOUT = 1.8 V)
Figure 5-3 Efficiency vs Output Current (VOUT = 3.3 V)

The total watts loss is relatively constant as the output voltage varies from 1.2 V to 3.3 V, but the output power varies with VOUT. This causes the measured efficiency to decrease markedly as the output voltage is lowered.

The transient response for a 50% load step (from 2.5 A to 7.5 A) is shown in Figure 5-4 for VIN = 12 V, and is essentially unchanged with VIN = 8 V or 5 V.

Figure 5-4 Output Voltage with 5-A Load Step