I am trying to measure input capacitance on the IN pin for the PI5V330S:
The yellow top trace is my input signal from an Agilent 80 MHz arbitrary generator: 1 MHz square wave, 5Vpp @ 2.5Vdc.
The three bottom traces are the results of my measurements under these conditions:
1) Open - the trace is actually cut so a piece of wire is shorting the trace back together. No part is in the socket so the trace is an open.
2) A 10kΩ resistor is soldered across the cut trace. No part is in the socket. Measured at the 'open' end of the resistor.
3) A 100kΩ resistor is soldered across the cut trace. no part is in the socket. Measured at the 'open' end of the resistor.
It is obvious that there is parasitic capacitances on the board. I calculate in the ~8 pF. I was hoping that is good news because then I would be able to place the part in the socket, and back calculate the pin capacitance since the part specifies 6 pF MAX. ASSUMING 6pF, then that is double the amount of capacitance so I should see that reflected in the rising edge of my square wave.
But I do not.
The waveform barely changes, so I must conclude that the pin capacitance is really, really, low or something else is amiss.
Any other suggestions (rather than an LCR meter - sucks BTW) to measure pin capacitance?
The yellow top trace is my input signal from an Agilent 80 MHz arbitrary generator: 1 MHz square wave, 5Vpp @ 2.5Vdc.
The three bottom traces are the results of my measurements under these conditions:
1) Open - the trace is actually cut so a piece of wire is shorting the trace back together. No part is in the socket so the trace is an open.
2) A 10kΩ resistor is soldered across the cut trace. No part is in the socket. Measured at the 'open' end of the resistor.
3) A 100kΩ resistor is soldered across the cut trace. no part is in the socket. Measured at the 'open' end of the resistor.
It is obvious that there is parasitic capacitances on the board. I calculate in the ~8 pF. I was hoping that is good news because then I would be able to place the part in the socket, and back calculate the pin capacitance since the part specifies 6 pF MAX. ASSUMING 6pF, then that is double the amount of capacitance so I should see that reflected in the rising edge of my square wave.
But I do not.
The waveform barely changes, so I must conclude that the pin capacitance is really, really, low or something else is amiss.
Any other suggestions (rather than an LCR meter - sucks BTW) to measure pin capacitance?
