DRV8701: SO datasheet figure misleads

Pietro Di Buono 88

Part Number: DRV8701

I'm writing because I would like to report misleading pictures in datasheet.
SO graph in Figure 37 doesn't match with electric circuit in Figure 22.
You would have to add a transistor in Figure 22 to pull-down SO pin when current hits the current chopping threshold.

Regards

Pietro

over 7 years ago

0 James Lockridge19 over 7 years ago

TI__Genius 14487 points

Hi Pietro,

Thank you for your feedback. Can you please show me where you would put the transistor to pull down the SO output to make the waveform the same?

Right now I think the datasheet is correct, but I might be missing something. When I look at the functional block diagram on page 13, the sense resistor is on the source of the low side FETs. During chopping, the sense resistor will only have a voltage across it when either of the low-side FETs are on. However, when the FETs are off, the sense resistor is 0 V. Figure 21 shows this also.

0 Pietro Di Buono 88 over 7 years ago in reply to James Lockridge19

Intellectual 360 points

I'm sorry,
you are right. I was wrong because I didn't consider the whole circuit.

Only fools don't admit their mistakes. Thanks for bringing me back on the right way!

Pietro

0 James Lockridge19 over 7 years ago in reply to Pietro Di Buono 88

TI__Genius 14487 points

Thanks for helping us stay honest about our datasheets! We want our datasheets to be the best they can be, so we always appreciate your feedback.

Have a nice day!

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DRV8701: SO datasheet figure misleads