# Is this prescaler suitable for my purpose

Discussion in 'General Electronics Chat' started by dumindu89, Sep 19, 2012.

1. ### dumindu89 Thread Starter Member

Oct 28, 2010
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I am going to use the SAB6456 prescaler and this have to divide the 90MHz to 110 MHz frequencies by 64.

Input voltage to the prescaler is 200 mV(p-p).

1. Is it possible to use this prescaler IC with this input voltage?
2. What should be the minimum input p-p voltage that can be applied for this prescaler?
3. How I find these minimum and maximum input voltages that can apply for the pin 2 and 3 in the datasheet?
4. What is mean by sensitivity to input voltage in the datasheet?
5. Do I really need to do a impedance matching?
Datasheet >> http://cs.utsource.net/goods_files/pdf/26/26127_TEMIC_U893BSE.pdf

6. Are there any prescaler which has divided by 8 option that satisfy my input voltage and frequency range?

2. ### Dodgydave AAC Fanatic!

Jun 22, 2012
5,005
745
The values are on page 2 of the datasheet, are you trying to input 90Mhz and hope to get out 110Mhz???

cos that wont work, it divides the input frequency by 64 /128 /256

Last edited: Sep 19, 2012
3. ### KMoffett AAC Fanatic!

Dec 19, 2007
2,577
231
I think the OP means a prescaler that divides by 64 an input signal that can range from 90MHz to 110MHz....output would range from 1.40625MHZ to 1.71875MHz

Ken

4. ### dumindu89 Thread Starter Member

Oct 28, 2010
113
0
Yeah.. you right.

I want to know that can this prescaler detect 200 mV (p-p) input signal and output the divided frequency?

and

4. What is mean by sensitivity to input voltage in the datasheet?
5. Do I really need to do a impedance matching?

5. ### KMoffett AAC Fanatic!

Dec 19, 2007
2,577
231
Look at the input sensitivity graph on page 5. That will tell you the minimum RMS voltage needed to trigger the circuit. Note the variation of sensitivity in relation to input frequency.

Matching the output impedance of your signal source will allow maximum power transfer, but not necessarily maximum input voltage.

Ken

6. ### Dodgydave AAC Fanatic!

Jun 22, 2012
5,005
745
Input sensitivity is 10mV to 20mV dependant on frequency input, page 5.

7. ### dumindu89 Thread Starter Member

Oct 28, 2010
113
0
According the sensitivity graph 10 mV to 300 mV is the guaranteed sensitive input voltage range for my desired frequency range which means this prescaler can be used for my purpose. Isn't it?

8. ### KMoffett AAC Fanatic!

Dec 19, 2007
2,577
231
Depending on good RF PCB layout practices, yes.

Ken

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