DRV8305: configuraion of IDRIVE and the relationship between IDRIVE and heating value

Takao Yamamoto

Genius 4135 points

Part Number: DRV8305

Dear all,

Could you teach about the configuration of IDRIVE and the relationship between IDRIVE and heating value?

■QUESTION 1, How value does this device heat according to IDRIVE configuration?

* I would like to know how power dissipation in this device in order to prevent over temperature protection.

■QUESTION 2, How should I think about maximum heating value in device? Is there culculation formula?

■QUESTION 3, What problem will happen if I set 1.25A sink and 1A source?

*According to paragraph of section 7.3.5.1 in datasheet, beyond 80mA (sink)/70mA (source) current settings, this device have worse accuracy.

I concern about this worse accuracy may occur some bad things.

Best regards,

over 6 years ago

0 Rick Duncan over 6 years ago

TI__Guru** 114905 points

Hi Yamamoto-san,

We will investigate and reply soon.

0 ming chen3 over 6 years ago in reply to Rick Duncan

Intellectual 775 points

I have the same question.please give me a feedback .
thanks

0 Takao Yamamoto over 6 years ago in reply to Rick Duncan

Genius 4135 points

Dear Duncan-san,

Thank you for you support.
How is your progress?
Could you inform me ASAP?

Best regards,

0 Takao Yamamoto over 6 years ago in reply to Rick Duncan

Genius 4135 points

Hi Duncan-san,

I would appreciate if you inform me when you could answer.

Best regards,

0 Phil Beard over 6 years ago in reply to Takao Yamamoto

TI__Expert 4650 points

Hi Yamamoto-san,

I will have an answer to you by the end of the day. We appreciate your patience.

0 Phil Beard over 6 years ago in reply to Phil Beard

TI__Expert 4650 points

Hi Yamamoto-san,

Q1 + Q2:

To calculate power dissipation in the device at specific IDRIVE settings, you can use the following equations:

GL_PWR: IDRV x PVDD x (∆T/T_PWM)
GH_PWR: IDRV x (2xPVDD) x (∆T/T_PWM)

Where:

GL_PWR = Gate Low Power Dissipation
GH_PWR = Gate High Power Dissipation
IDRV = IDRIVE Current Setting
PVDD = Device Supply Voltage
∆T = Actual Slew Rate in your application, so the time from when the MOSFET is off to when it is fully turned on (VGS = VCP)
T_PWM = Period of your PWM frequency

Q3: Accuracy will be slightly degraded, but the device will still function properly across each channel.

For more information on our IDRIVE / TDRIVE technology, we have an app note available here for review:
www.ti.com/.../slva714a.pdf

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DRV8305: configuraion of IDRIVE and the relationship between IDRIVE and heating value