SLVAFH6 November   2023 LM25066 , LM5066 , LM5066I , TPS25984 , TPS25985 , TPS25990 , TPS536C9T

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2What are PSYS™ and PSYS_CRIT#™?
  6. 3Implementation of PSYS Monitor
    1. 3.1 Existing Designs
    2. 3.2 Proposed Designs
  7. 4ISYS Resistor (RISYS) and Gain (ISYS_IN_GAIN) Selection in TPS536C9T VR14 Controller
    1. 4.1 Steps to Calculate the Value of RIMON or RISYS and ISYS_IN_GAIN
    2. 4.2 Design Example
  8. 5Functional Verification of PSYS and PSYS_CRIT# in TPS536C9T VR14 Controller Using TPS25984, TPS25985, or TPS25990 eFuses as PSYS Monitor
  9. 6Extraction of Platform Current Information With Multiple PSYS Monitors Connected to the Same PSU
    1. 6.1 Designing the Non-Inverting Summing Amplifier
    2. 6.2 Design Guideline and Example
  10. 7Summary
  11. 8References

4.1 Steps to Calculate the Value of RIMON or RISYS and ISYS_IN_GAIN

  1. Find out the full-scale range of ISYS_IN pin in the VR14 controller.
  2. Set the VIREF to half of the maximum voltage range of the ISYS_IN input of the VR14 controller. This provides the necessary headroom and dynamic range for the system to accurately monitor the load current up to the scalable fast-trip threshold (2 × IOCP).
  3. Calculate the value of RIMON or RISYS using Equation 3 to set the appropriate over-current protection or circuit-breaker threshold for eFuses.
  4. Finally, select the internal scaling factor ISYS_IN_GAIN (set through the SVID_CONFIG) according to Equation 6.
Equation 6. I S Y S _ I N _ G A I N = 1 G I S Y S × R I S Y S