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TPS28226: what's the capacitance value of LGATE and UGATE pin ( including parasitic capacitance )?
Thank you for supporting the customer with the TPS28226. For the question of the parasitic capacitance I have some questions since this will not be easy to measure since the internal device on state of the pull up and pull down will dominate any device capacitance.
What is the concern of the customer on the pin capacitance? Is the parasitic capacitance of interest when the device is not powered by VDD? Is the customer interested in the UGATE capacitance relative to GND or relative to PHASE?
The driver outputs will have the internal pull up and pull down devices connected. These devices do have output capacitance and well as parasitic body diodes. When the devices are switching, the device Rdson dominates any parasitic capacitance as seen by the external circuit.
The only way you would see parasitic capacitance would be very low level signals, less than body diode drop, and with the device not powered by VDD.
Please confirm the customers concern, or confirm if this addresses your question.
Although the input capacitance of the PWM pin is not a specified parameter, I did confirm that the parasitic capacitance of this input pin will be very low, in the 3pF range which is typical of many devices control pins. It is likely the parasitic board capacitance and maybe the device driving the PEM pin will dominate the capacitance on this signal.
Let us know if this addresses your question, or you can post additional questions on this thread.
