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

5.1 Control Loop Characteristics

A signal can be injected across R12 at TP3 and TP6 to examine the gain and phase frequency response of this circuit with a network analyzer. Figure 5-5 and Figure 5-6 detail the loop gain and phase with VIN = 5 V and VIN = 12 V. Due to the feedforward circuitry implemented in the circuit, the gain is seen to be relatively constant as VIN varies more than 2 to 1. There is approximately 50 degrees of phase margin at the loop crossover frequency near 45 kHz.

Figure 5-5 Gain/Phase vs Frequency (VIN = 5 V)
Figure 5-6 Gain/Phase vs Frequency (VIN = 12 V)