LAUNCHXL2-RM57L: Can't read 10-15 Mc/s pulses of 35 nanosecond pulse width, suggest a counter IC

Hello Apurv,

you are already on the right way with searching for an external fast enough counter for your case.

First let me know the characteristics of the output signal from your photon counting module.

I mean amplitude voltage and what is the minimum time between pulses.

One cheap solution can be

but you must check carefully for the input clock high/low level minimum timings.

Next step will be parallel outputs connection to the chip for fast reading of the result.

Start and stop e.g triggering on and off the counter can be done through CLR input of the chip.

Michail

Hey, Michail, thanks for the reply!

The output characteristics of my module are the following:

• maximum counts = 15,000,000 per second
• pulse width = 35 nanoseconds
• voltage = 0-3.3 V
• dead time (minimum time between pulses) = 50 nanoseconds

I came across http://www.ti.com/lit/ds/symlink/sn74lv8154.pdf 

Regards,
Apurv

Hi,

yes, this chip also should work out the case. Note just one thing that timing specifications are given for 5V Vcc.

With 3.3V supply they may differ and If this worsened the parameters too much you'll need to add a fast one directional level shifter 3.3 -> 5V and supply the 74LV8154 with 5V.

BR

Michail

How do we interface it with the micro-controller board? It can't be directly connected to 8pins of the board, right?

Thank you.

Just one last confirmation/question, sir.

These counter ICs will be able to read input digital pulses of 35 nanoseconds, right?

Thanks and regards,
Apurv

Hello,

yes, according to datasheet of 74LV8154. Table 6.6

BR

Michail