Question about design circuit of TPS386000

Satoshi

Guru 19485 points

Customer design following circuit.

※Vsense：①+5.0V、②+3.3V、③+4.5V

　⇒Vth：①+4.5V、②+2.9V、③+4.2V

【Problem】

Though the Vsense voltage of everything exceeds Vth (5V or 3.3V), a reset signal is a condition of "Low".

Is there a mistake in a circuit diagram?

(Are MR, CT and Watchdog OK?)

Please let me know.

Best regards,

Satoshi

over 9 years ago

0 David Hopkins over 9 years ago

TI__Expert 8905 points

Hi Satoshi,

There should not be pull-up resistors on the Ct pins - this could cause the device to have the reset as low.

Regards,
David

0 Satoshi over 9 years ago in reply to David Hopkins

Guru 19485 points

Dear David-san

Thank you for reply.

Customer changed CT-pin only Vcc+200kΩ pull up, but the result was same.

I think that 4.7kΩ pull up (Reset, MR, WDO) is too small, is it correct?
When there are other correction points, please let me know.

Best regards,
Satoshi

0 David Hopkins over 9 years ago in reply to Satoshi

TI__Expert 8905 points

Hi Satoshi-san,

Just to make sure I correctly understood your previous statement, the customer removed the 200kOhm resistor and it still did not function?

The resistor should be ok but only by a slim margin - 10k would be preferred. What is the measured voltage on MR/?

Regards,
David

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Question about design circuit of TPS386000