• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 30 subscribers
  • Views 562 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV8305 : VGHS is higher than spec.

Kazumichi Shirai
Prodigy 250 points
Other Parts Discussed in Thread: DRV8305

I use DRV8305 to control brush-less motor.

The attachment is the waveform of PVDD, V at SLC, V at GHC, V at GLC of DRV8305 when DRV8305 controls a brush-less motor (rotation speed is 1200rpm).
VGHC (voltage at GHC) looks very high and has two steps(24V/35V), but VGCH must be less than 10.5V accroding to datasheet.
Could you tell me why my PCB has such a problem? What parameters shold I adjust.
Give me the advice to use DRV8305 correctly.

Thank you in advance,
Shirai

  • 0
    TI__Guru** 114905 points
    Hi Sharai,

    Vgs appears to be correct. The voltage is the gate voltage - the source voltage, which is about 11V in your scope capture.

    Two steps is also normal. When turning off the low side, the phase voltage can increase to approximately PVDD. This will cause the gate of the high side to rise to PVDD until the high side is turned on. Once turned on, the gate voltage (Vgs) should be typically 10V above the SHx (source) voltage.
  • 0 in reply to Rick Duncan
    Prodigy 250 points
    Hi Rick-san,

    Thank you for your answer.
    I understand clearly.

    Shirai