• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 2 answers
  • Subscribers 62 subscribers
  • Views 790 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

LMG1210: 5V clamp current limit for regulation

Michael T Schneider
Expert 3780 points
Part Number: LMG1210
Other Parts Discussed in Thread: LMG1205,

Hello Team,

One of my customers is looking to use the LMG1205 in a 100% duty cycle application. They also have ~100uA of gate to source leakage on the top side driver output. The engineer would like to pull HB up to an 8V source through a current limiting resistor to keep HB charged to 5V. However, I don’t have specifications on the 5V clamp inside the LMG1205, so I can’t determine how much current the clamp can support while maintaining regulation.  Are there any details of that clamp you can share we met so I can advice the engineer?

 Ideally they woud just drive HB with low impedance 5V themselves, but they are worried the clamp could be under 5V and thus burn lots of power.

 Block diagram below.

 Thanks,

  • 0 in reply to Michael T Schneider
    TI__Prodigy 645 points

    Hi Michael,

     Your title and the body of your message do not agree on the half-bridge driver you are using (LMG1210 and LMG1205), however neither part actually has a shunt clamp which can sink current between HB-HS. The LMG1205 "clamp" works by disabling the bootstrap diode and therefore the current charging path when the bootstrap voltage is high enough. The LMG1210, as stated in the datasheet, works by disabling the bootstrap diode during the dead times which stops the overcharging of the bootstrap voltage. Neither part will sink current when the bootstrap voltage goes above 5V.

    So, putting a resistor from HB to HS+8V is not recommended as there is nothing to stop HB-HS from going to 8V. However, if you can make the HS+8V be HS+5V, you can just directly connect that to the HB pin and it will work great.

    Regards,

    Nathan