DRV110EVM: R3 value

Tester1002

Prodigy 20 points

Part Number: DRV110EVM
Other Parts Discussed in Thread: DRV110

Hi,

Can someone explain to me to how to size R3.

Let's say DCSUPPLY = 24VDC and I peak <= 500mA.

Thanks.

8 months ago

0 Tester1002 8 months ago

Prodigy 20 points

Please ignore this question. It is already explained in the parameter calculator sheet.

Thanks.

0 Jacob Thompson 8 months ago in reply to Tester1002

TI__Genius 17998 points

Glad you figured it out, let us know if you have any other questions! Also that part is very old, I highly recommend looking into using one of our newer half-bridge drivers such as the DRV8932 or DRV8962

Regards,

Jacob

0 Tester1002 8 months ago in reply to Jacob Thompson

Prodigy 20 points

Hi Jacob,

Thank you for the reply.

The param sheet requires I_Aux value. Can you explain where this value can be referred to?

Thanks.

0 Jacob Thompson 8 months ago in reply to Tester1002

TI__Genius 17998 points

Hello,

I can't seem to find I_Aux anywhere in the DRV110 datasheet or EVM users guide - can you point me to where you're finding this? I'm not sure what parameter sheet you're referring to

+1 Tester1002 8 months ago in reply to Jacob Thompson

Prodigy 20 points

Hi Jacob,

It is in the 'DRV110 Zener' tab of parameter selection tool sheet https://dr-download.ti.com/design-tools-simulation/calculation-tool/MD-IA7wcYcSgz/01.00.00.00/slic024.zip provided in the following page:

https://mobile-dev.aws.ti.com/product/DRV110

I assume Rs in used in the name of R3. And that the formula used to obtain Rs depends on I_Aux.

Also I have found equations 5 and 6 on DRV110 datasheet a more direct method to obtain Rs value.

Equation 5:

where IGate,AVE equals the Mosfet gate charge multiplied by fPWM.

The table below is extracted from Mosfet STD1NK60T4 (original Mosfet on the EVM) datasheet:

What can be used to define the Mosfet 'gate charge' and 'fPWM' values?

Regards.

0 Jacob Thompson 8 months ago in reply to Tester1002

TI__Genius 17998 points

Hello,

The I_Aux is used to calculate the Rs (kΩ) value with: (Vs_min - 15V) / (I_Zener + AverageGateCurrent + I_Aux) in the sheet.

We're still looking into this. My best guess right now is that it's the IQ standby current, quiescent current, or IVIN. I'll let you know what my more experienced team members respond with in a day or two.

Regards,

Jacob

0 Jacob Thompson 8 months ago in reply to Jacob Thompson

TI__Genius 17998 points

Tester1002 said:
What can be used to define the Mosfet 'gate charge' and 'fPWM' values?

Mosfet gate charge should be parameter Qg in your particular MOSFET's datasheet as you show.

fPWM is the switching frequency of your PWM signal for controlling the solenoid current. This can be from 15kHz to 27kHz according to the electrical characteristics table. It can be from 7.5% duty cycle to 100% duty cycle. Also see 7.3.2 PWM Current Control.

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DRV110EVM: R3 value