SLVAFD6 July   2022 TPS564247 , TPS565242

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2Analysis of the Floating-Input Pre-bias Output Operation
    1. 2.1 Analysis of FCCM Device
    2. 2.2 Analysis of PSM Device
  5. 3Experimental Verification
    1. 3.1 FCCM device
      1. 3.1.1 Bias Voltage > Target
      2. 3.1.2 Bias Voltage < Target
    2. 3.2 PSM device
      1. 3.2.1 Bias Voltage > Target
      2. 3.2.2 Bias Voltage < Target
  6. 4Summary
  7. 5References

3.1.1 Bias Voltage > Target

In the experiment, the target output voltage is 5 V, bias output is 5.05 V. From the test result in Table 3-1, the calculated input voltage based in Equation 5 is 20 V. The measured value is 18.4 V, it has exceeded the absolute max value in data sheet, it may cause permanent device damage.

Table 3-1 Test Result of Vbias>Vtarget in FCCM Device
Test device Vbias Fsw L INOC(measured) Vin from Eq(5) Vin measured
TPS565247 5.05 V 574KHz 1.1uH 3.08 A 20V 18.4 V
GUID-20220623-SS0I-8PZC-M4KQ-GFCGJFD2MBL6-low.png Figure 3-2 Test Waveform of Vbias>Vtarget in FCCM Device