DRV8323: Is VCP in Figure 26 supposed to be VGSH?

Danilo A.

Part Number: DRV8323

Hi Team,

Section 8.3.1.3 of the datasheet states that if VM is less than 12V, VVCP = 2 x VVM-1.5V. Example, If VM is 10V then VVCP = 2 x 10 - 1.5V = 18.5V. Is this correct?

However, the Figure 26 of the DRV8323 datasheet shows the VCP pin is connected to the Drain pin of the internal high-side MOSFET. Therefore the output to the GHx pin will exceed the VGS of the external MOSFET. Is the VCP pin in Figure 26 supposed to be VGSH? If not, how is the output at GHx pin regulated to within the limit of VGS of the external MOSFET?

Regards,

Danilo

over 4 years ago

0 Matt Hein over 4 years ago

TI__Mastermind 21805 points

Hi Danilo,

The high-side gate driver has a VGS clamping diode to ensure that the voltage applied to the high-side gate never exceeds around 15V.

Practically, this clamping diode does not often conduct current. When turning ON the high-side MOSFET current is driven into the gate to charge it. After crossing the miller plateau, the switching node will rise up to the supply. After this, the gate is charged to supply + 10V (VCP).

The full VCP is not directly applied to the MOSFET since the gate driver acts as a resistive path to charge the MOSFET gate..

Thanks,

Matt

0 Mladen Bruck over 4 years ago in reply to Matt Hein

Prodigy 70 points

Hi Matt,

Great to know that gate is never goes above 15V.

But this is confusing:

Matt Hein said:
After this, the gate is charged to supply + 10V (VCP).

Which supply? What this mean "supply + 10V (VCP)"? VCP + 10V?

Is this clamping diode you talking about ?

Thanks,

Mladen

0 Matt Hein over 4 years ago in reply to Mladen Bruck

TI__Mastermind 21805 points

Hello Mladen,

Yes, that is the clamping diode I was referring to.

The "supply" in this case is VM (i.e. the motor power supply). VCP is regulated to be VM+10V.

Thanks,

Matt

0 Matt Hein over 3 years ago in reply to Matt Hein

TI__Mastermind 21805 points

Hello Mladen,

Do you have any further questions on this thread?

Thanks,

Matt

0 Mladen Bruck over 3 years ago in reply to Matt Hein

Prodigy 70 points

Hi Matt,

Thank you for support. I have no more questions about this.

BR,

Mladen

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DRV8323: Is VCP in Figure 26 supposed to be VGSH?