DRV8320R: IDRIVE characteristic

yeonsu kim

Prodigy 30 points

Part Number: DRV8320R
Other Parts Discussed in Thread: DRV8320

We are using DRV8320RH for our motor-driver circuit.

I want to know 1) the implemented method of IDRIVE at DRV8320RH,

and 2) IDRIVE behavior when we apply software dead-time between INHx and INLx.

1) the implemented method of IDRIVE at DRV8320RH

According to the technical document(Understanding smart gate drive,slva714d),

there are 2 kinds of implemented method of IDRIVE such as multiple switches, current source.

What is implemented method of IDRIVE at DRV8320RH? multiple switches or current source.

2) IDRIVE behavior when we apply software dead-time between INHx and INLx

If we apply software dead-time(1us) from MCU ( so, INLx turn-off and INHx turn-on is not switched at the same time),

what is the IDRIVE behavior? case1 of case2?

① case1

② case2

over 1 year ago

0 Joshua Horlander Cruz over 1 year ago

TI__Genius 14700 points

Hi Yeonsu,

yeonsu kim said:
1) the implemented method of IDRIVE at DRV8320RH

I will need to look into this, I will aim to get you a response by tomorrow.

yeonsu kim said:
2) IDRIVE behavior when we apply software dead-time between INHx and INLx

The behavior of the device will be similar to case 1.

Best Regards,

Joshua

0 yeonsu kim over 1 year ago in reply to Joshua Horlander Cruz

Prodigy 30 points

Thank you for quick reply.

About question 2), then, Is this timing-response correct?

(rising edge of VGHx is delayed to starting point of high-side Idrive)

※ our setting value

. turn-on time=200ns, turn-off time=200ns

. dead-time of DRV8320RH = 100ns

. software dead-time by MCU = 1us

+1 Joshua Horlander Cruz over 1 year ago in reply to yeonsu kim

TI__Genius 14700 points

Hi Yeonsu,

I deeply apologize, I made a mistake, case 2 will be the more similar behavior not case 1.

To prevent parasitic coupling from the switching MOSFET from turning on the opposite MOSFET ISTRONG, a strong current lasting the duration of TDRIVE, will pulldown the opposite MOSFET when a MOSFET is switching.

yeonsu kim said:
1) the implemented method of IDRIVE at DRV8320RH

The DRV8320RH uses the multi-switch IDRIVE implementation.

Best Regards,

Joshua

0 yeonsu kim over 1 year ago in reply to Joshua Horlander Cruz

Prodigy 30 points

Hi Joshua,

Thank you for your reply.

Could you explain a little bit more?

I'm curious the equivalent resistance of low-side gate signal line between GLx-pin and GND

for TDRIVE(pulldown ISTRONG) duration when high-side is turn-on.

According to the datasheet of DRV8320,

Peak value of ISTRONG is 2A and VGLx is 11V when Vvm is over 12V.

then, I guess the equivalent resistance is about 11V/2A=5.5Ohm.

is it correct?

+1 Joshua Horlander Cruz over 1 year ago in reply to yeonsu kim

TI__Genius 14700 points

Hi Yeonsu,

Sorry, but we cannot provide exact equivalent resistance of the low-side gate signal line between the GLx-pin and GND.

The equation you used is correct but since the FET must have been previously turned off before ISTRONG is used, VGLS will be lower than 11V when ISTRONG is active.

Thank you,

Joshua

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DRV8320R: IDRIVE characteristic