DT9837A - external trigger signal

[GEARTEC.CZ]

I am a user of DT9837A-OEM board. I am, however, facing an issue with a trigger input signal. In the description on the website, there is that the external trigger shouble be a TTL signal compatible (TTL standard is 0-5V) and that the system detects a rising edge only. By connecting a standard TTL trigger, the board does not detect anything. In the user manual (dowloaded directly from the webpages), however, there is written that the signal should be LVTTL (1,1-1,3V) - netiher this works. It also talks about the minimum pulse width as of 1,3 uA (microAmper) that seems strange to me. Is here anyone who could reliably answer my questions below?

- What external trigger input is exepcted? (TTL, LVTTL or different)?
- What is the lower / upper treshold?
- What is the minimum pulse width in ms or ns (milliseconds or nanoseconds)?
- What is the current?

Thank you to you all!

[JRys]

Hello,

The external digital trigger uses an op-amp comparator circuit set to switch at levels above 1.3v and is protected up to 5v. Therefore, using a 5v TTL signal is acceptable. The low-level threshold is 1.1v, and the input current is 33uA. The pulse width spec of 1.3uA is a type-o and should have been written 1.3uS (microseconds).

Best regards,

John