SDAA080 September   2025 TPS2HCS08-Q1 , TPS2HCS10-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2High Side Switch Current Sense and Open Load Detection
    1. 2.1 Current Sense in High-side Switches
    2. 2.2 Open-Load Detection in High-side Switches
  6. 3Smart eFuse Current Sense and Open Load Detection
    1. 3.1 Open Load Detection in eFuses
    2. 3.2 Open-Load Current Sense Scaling
    3. 3.3 ADC Input Scaling
    4. 3.4 OL_ON and ADC Input Scaling Programming Procedure
  7. 4Normal vs. Open-Load Scaling Test Results
  8. 5Design Considerations
  9. 6Summary
  10. 7References

3.2 Open-Load Current Sense Scaling

As an example, TPS2HCS08-Q1's default current sense scaling factor is KSNS = 5000A/A – that is, ISNS = IOUT / 5000. During load currents above 10A, this KSNS1 accuracy is exceptional at +/- 4%. However, as the load current decreases, the accuracy gets worse due to the nature of the circuit, and the KSNS1 accuracy at 100mA is +/- 18%. At lower currents, this accuracy gets exponentially worse.

To improve accuracy at low currents, TI Smart eFuses implement an OL_ON mode. In this mode, taking TPS2HCS08-Q1 as an example, the KSNS value is reduced from 5000A/A to 1400A/A (KSNS2), and the FET ON resistance is increased from 8.7mΩ to 27mΩ, allowing for a much higher current sense accuracy at low currents. In this case, the KSNS2 accuracy at 100mA is +/- 10%, and currents can be read reliably down to 10mA via SPI.