Page History

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• Using Rhode & Schwarz HMP4030 power supply
• Only P24V0D connected to channel 2 of the supply
• Using board 38-C00-02
• Started with a current limit set to 10 mA
• Increased the current limit by 1 mA steps until the supply went out of constant-current mode
  • This happened at around 130 mA
  • Board is consuming 128.2 mA and is steady
  • This is 3.08 W
  • Lukewarm around the first stage DC/DC converter
• Set the current limit to 160 mA for now
• Test points:
  • P5V0 EN = 2.179 V
  • P5V0 = 4.988 V
  • P0V85 = 0.852 V
  • P0V9 = 0.906 V
  • P1V2 = 0.103 V
  • P1V8 = 0.031 V
  • → This seems to indicate that the power sequencing is not working as intended
  • The following enable signals must be > 41.5 3 V (Enable threshold voltage) for the DC/DC converter (TPSM5D1806) to enable its output:
    • ENABLE_P0V9 (R53/R57) = 1.865 V This is not > 4.5 V but the P0V9 output is still on???→ OK
    • ENABLE_P1V2 (R70/R71) = 1.163 V → NOK
    • ENABLE_P1V8 (R54/R58) = 1.163 VV → NOK
  • The issue is that the dividers R70/R71 and R54/R58 are essentially in parallel due to the 0R resistors R21 and R22
    • → Remove one of the dividers