SLVUBI1 May   2021


  1.   Trademarks
  2. 1TPS7H4002EVM-CVAL Overview
    1. 1.1 Features
    2. 1.2 Applications
  3. 2TPS7H4002EVM-CVAL Default Configuration
  4. 3TPS7H4002EVM-CVAL Initial Setup
  5. 4TPS7H4002EVM-CVAL Testing
    1. 4.1 Output Voltage Regulation
    2. 4.2 Output Voltage Ripple
    3. 4.3 Soft Start-up
    4. 4.4 Transient Response to Positive/Negative Load Step (0 A to 3A to 0A)
    5. 4.5 Input Voltage Ripple
    6. 4.6 Loop Frequency Response
    7. 4.7 Current Limiting
  6. 5TPS7H4002EVM-CVAL EVM Schematic
  7. 6TPS7H4002EVM-CVAL Bill of Materials (BOM)
  8. 7Board Layout

Loop Frequency Response

Measuring the frequency response of the feedback loop requires a unique test setup as well as physical changes to the EVM. The 0-Ω resistor jumper R9, just above the output inductor, L1, must be lifted to break the loop. Both test points TP20 (BODE) and TP15 (VOUT) are used for connections to the Bode100 instruments.

GUID-20210518-CA0I-WCTJ-BJSV-PNZRSDM39GPH-low.png Figure 4-7 EVM Modification to Measure Frequency Response

The test setup which includes several connections to Picotest Bode100 test instruments is shown in Figure 4-8. Measurement results are shown in Figure 4-9 and in Figure 4-10. The CHF, high frequency pole, component of the compensation circuit is optional. Omitting it results in slightly increased phase margin. However, the benefit of including it is that the gain curve is set in a downward trajectory as frequency increases, making a monotonic gain curve more likely to be achieved.

GUID-20210517-CA0I-RK7V-MSWZ-NX676WSJSNBP-low.png Figure 4-8 Frequency Response Test Setup
GUID-20210517-CA0I-GTLD-JCRB-G7P08VSH5DCB-low.png Figure 4-9 Frequency Response IOUT = 3 A
GUID-20210517-CA0I-CKZ1-F8Q7-3B1QHBNVHQNG-low.png Figure 4-10 Frequency Response IOUT = 0 A