I'm disty of Japan.
I have some questions on VFC110.
****** Background ***************
My customer is evaluating VFC110 with the evaluation board which he designed.
He intend to change "fFS = 4MHz or 2MHz" by changing external components(RIN, Cos).
External components setting are as follows.
・fFS=4MHz(VIN＝10V): (RIN,Cos)=(25kΩ ,non-mounted)
・fFS=2MHz(VIN＝10V): (RIN,Cos)=(34kΩ,56pF)
＊25kΩ(TYP) from data sheet P6, Figure1.
The result when he evaluated the VFC110 circuit with above conditions is as follows.
・fFS＝4.7MHz(VIN＝10V)： (RIN,Cos)=(25kΩ ,non-mounted)
・fFS=2MHz(VIN＝10V): (RIN,Cos)=(34kΩ,56pF)
＊the output frequency was 4.7MHz,it was different from expected value.
So, he measured internal resistance value between 1pin and 2pin.
Its value was about 34kΩ(6 samples).
When he evaluated it as RIN=34kΩ, the output frequency was about 4MHz(=fFS:VIN=10V).
****** Questions **********
Q1:Is the internal resistance value a little higher actually,though its value is mentioned 25kΩ±20%
with the data sheet(P6 Figure1)?
Q2:He intend to design the value of external resistance(RIN) as 34kΩ.
Is his understanding correct?
Best regards.