VFC110: VCF110 Comparator Input response time

Varunesh Kumar

Intellectual 840 points

Part Number: VFC110

Hello

We are going to use VFC110 as an F to V converter accepting Freq from 2 to 3 MHz.

We receive this Freq via FO Receiver AFBR 2624Z, wave shape by a Schmitt Trigger,

then differentiate to create a narrow Negative Going Pulse.

My Q;s are:

1. What is the Response time for the Internal Comparator " tres " in nSec?

2. The Max Neg going Pulse Width your Data Sheet recommends as 1/10th of the Min Cycle Time

in our case the Cycle Time would be 333 nS for 3 MHz, so a 33.3 nS would be the Max.

What is the Min Neg going Pulse Width reqd to Trigger the internal Comparator?

The Ckt is shown below:

Thanks in advance.

over 4 years ago

0 Kaushik Prajapati over 4 years ago

Intellectual 310 points

The circuit is shown below-

0 Thomas Kuehl over 4 years ago

TI__Guru* 93105 points

Hello Varunesh,

The VFC110 is a legacy product from the 1980s and any detailed information about such things as internal comparator response time is no loner available. I searched the paper archive and although some minimal documentation exists for the VFC110 I found nothing that mentioned timing.

It is reasonable to assume that the response time of the VFC's comparator must be considerably faster than the 4 MHz fastest frequency of operation. If we take the reciprocal of 4 MHz, that is 250 ns; thus, the response needs to be a fraction of this time.

Unfortunately, we do not have any information about the minimum negative going pulse width that will trigger the comparator. I suggest using the 1/10th minimum cycle time recommended in the datasheet.

Regards, Thomas

Precision Amplifiers Applications Engineering

0 Varunesh Kumar over 4 years ago in reply to Thomas Kuehl

Intellectual 840 points

Thanks Thomas for your diligent work of

digging up old archives..

Greatly appreciate.

Varun

Amplifiers

Amplifiers forum

VFC110: VCF110 Comparator Input response time