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

6.1 Designing the Non-Inverting Summing Amplifier

A high bandwidth (>= 50 MHz) and low offset (<= 100 μV ) precision op amp, for example, TLV365, is selected here to implement the non-inverting summing amplifier as shown in Figure 6-2.
GUID-20231009-SS0I-JXQS-0R0T-P7HNN8ZXRV5D-low.svg Figure 6-2 Non-Inverting Summing Amplifier to Aggregate the IMON Voltage Outputs From the Individual eFuse Modules

VIMON-1, VIMON-2, VIMON-3, ... , and VIMON-N are the IMON voltage outputs from the individual eFuse modules as defined in Equation 8.

Equation 8. V I M O N - 1 V = I I N - 1 A × R I M O N - 1 Ω × G I M O N μ A / A V I M O N - 2 V = I I N - 2 A × R I M O N - 2 Ω × G I M O N μ A / A V I M O N - 3 V = I I N - 3 A × R I M O N - 3 Ω × G I M O N μ A / A V I M O N - N V = I I N - N A × R I M O N - N Ω × G I M O N μ A / A

N is the number of current monitoring outputs, summed up using the summing amplifier. The voltage output of the summing amplifier in Figure 6-2 is described in Equation 9.

Equation 9. V I S Y S V = ∑ n = 1 N V I M O N - n V × m n

m1, m2, m3, ... , and mN are the different mathematical functions (f1, f2, f3, ... , and fN respectively) of RIN-1, RIN-2, RIN-3, ... , and RIN-N in Figure 6-2 as depicted in Equation 10.

Equation 10. m 1,2 , 3 , … , N = f 1,2 , 3 , … , N R I N - 1 , R I N - 2 , R I N - 3 , … , R I N - N

m1, m2, m3, ... , and mN need to be selected in such a way that Equation 11 is satisfied.

Equation 11. m 1 × R I M O N - 1 = m 2 × R I M O N - 2 = m 3 × R I M O N - 3 = … = m N × R I M O N - N

Equation 11 simplifies Equation 9 to Equation 12.

Equation 12. V I S Y S V = m 1 × R I M O N - 1 Ω × G I M O N μ A / A ∑ n = 1 N I I N - n A

ISYS_IN_GAIN, which needs to be programmed in the VR14 controller firmware to get the total platform current from the voltage at the ISYS pin, is obtained using Equation 13 in this architecture.

Equation 13. I S Y S _ I N _ G A I N = 1 m 1 × R I M O N - 1 × G I M O N

The procedure to compute m1, m2, m3, ... , and mN are discussed in Section 6.2.