I am looking at the pulse and direction input lines on a EN-204 drive by Control Techniques / Emerson and have a question about driving them from the Kflop.

I think 24 user I/O lines from the Kflop are 5V tolerant. The EN-204 states that the pulse and direction pins if you use single ended are TTL level (the drive can also take differential pulse inputs as well as analog velocity/torque command voltages).

The actual statement is: TTL, 330 ohm pull-ups to internal 5 V, 1.5 V = low, 3.5 V = high

Since the Kflop is 5V tolerant on the 24 I/O lines, I am assuming the 330 ohm pull-up to 5V will be fine and will make a high level greater than 3.5V. What about sinking? Can the Kflop sink enough current to pull the line below 1.5V? That would be 3.5V/330 ohm = 10.6mA but for safety, something greater than 15mA would be comfortable. I could not find info on the webpage about how much current the 5V tolerant I/O lines can sink.

Thanks for any help

Nevermind, I found the info on the Spartan3 pins that says they can sink 16mA. The I/O is clamped with an internal diode limited to 100mA. This sounds like the 330ohm pullup to 5V on the pulse input to the EN-204 drive will not be a problem. The output from the Kflop of 3.3V, clamped to around 4V pulled up to 5V inside the EN-204 would mean the current in the clamp diode would be only 3mA.

--- In DynoMotion@yahoogroups.com, "Roland" <lightdoesnotage@...> wrote:
>
> I am looking at the pulse and direction input lines on a EN-204 drive by Control Techniques / Emerson and have a question about driving them from the Kflop.
>
> I think 24 user I/O lines from the Kflop are 5V tolerant. The EN-204 states that the pulse and direction pins if you use single ended are TTL level (the drive can also take differential pulse inputs as well as analog velocity/torque command voltages).
>
> The actual statement is: TTL, 330 ohm pull-ups to internal 5 V, 1.5 V = low, 3.5 V = high
>
> Since the Kflop is 5V tolerant on the 24 I/O lines, I am assuming the 330 ohm pull-up to 5V will be fine and will make a high level greater than 3.5V. What about sinking? Can the Kflop sink enough current to pull the line below 1.5V? That would be 3.5V/330 ohm = 10.6mA but for safety, something greater than 15mA would be comfortable. I could not find info on the webpage about how much current the 5V tolerant I/O lines can sink.
>
> Thanks for any help
>