I cannot find any response time formulas for the LM2907 on any data sheets. Does anyone know if there is one?
Hi Michael,
The datasheet and the online AN-162 Applications Note that provide information about the LM2907-N do not make specific mentions of response time. It is relatively slow device topping out with a maximum input frequency of about 10 kHz in tach-to-voltage (F-to-V) operating mode. Most references to speed, or frequency in the datasheet are with 200 Hz, or 1 kHz.
About the only information in the datasheet that provides some idea of response time is the Section 10.2.1.3, Application Curves repeated below.
We can see that for this set of C1, C2 and R1 values that as the frequency is shifted from 68 Hz to 136 Hz, it takes at least 250 ms for the output voltage to stabilize at the final 136 Hz related voltage level. If the frequency is higher and the C1, C2 and R1 values chosen to be more suitable for that frequency the response time should be faster.
I suppose the LM2907-N is not the device to use if speed and fast response are required.
Regards, Thomas
Precision Amplifiers Applications Engineering
