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Hi,
There is a problem that voltage leaks to the source side (OUT pin) at the timing when voltage is applied to the drain side (VS pin).
Please check the following waveform. CH1 is OUT and CH2 is VS.
Is that normal behavior?
If yes, could you tell me the general measures?
If you need to discuss by checking customer's schematic, I would like to contact you via email or private message.
Best regards,
Yuto Sakai
Hi Cameron-san,
Thank you for your reply.
The attached waveform measurement conditions is no load.
The voltage peak also changes depending on the connected load.
This phenomenon occurs when the light load is connected.
Is it normal operation for this leakage voltage to occur before the device is turned on?
If our customer want to suppress this voltage, could you provide external measures?
Best regards,
Yuto Sakai
Hi,
I apologize for pushing you.
Our customer will fix the circuit soon.
I appreciate if you give me your answer.
Best regards,
Yuto Sakai
Sakai-san,
I believe this is because when you have an open load and you have a dV/dt on the device the gate is charged up by the capacitance on it. However this should not happen when you have a load attached to it as it will be pulled low.
Also if they are wanting to have open load detection in the off state they need to include a pullup resistor on the output which will make the output go high during an open load condition and a fault will be indicated.
Hi Cameron-san,
Thank you for your reply.
Customers do not want to detect open load when device is off.
At startup, They want to suppress the output voltage when the device is off and the input voltage starts up.
In the following post, the method to add load resistance was proposed as a measure to reduce the output voltage level.
Is this the recommended measure for TPS1H100?
http://e2e.ti.com/support/power-management/f/196/t/809561?tisearch=e2e-sitesearch&keymatch=TPS4H000#pi320995=1
Best regards,
Yuto Sakai
Sakai-san,
Yes adding the load resistance will make it to where you do not see this rise in voltage on the output.