USB DIO-96H voltage drop issue

[Liron Yitzhaki]

We are using USB DIO-96H device and found an issue.

when change DO to high on the device we measure 5v, however when we connect a resistor of 40Kohm in serial to the DO, there is a voltage drop to 3.7v, also we change the resistor to 2Kohm and measure 3.3v.

For my knowledge we expected to measure 5v as a "push-pull" configuration.

Can you explain why there is a voltage drop and what can I do in order to obtain the 5v?

Thanks,

[DAQman]

The USB-DIO96H's digital output chip is an SN74ABT244, which guarantees a high voltage above 2.0 only. This is also reflected in our device specifications in the user manual. 47k ohm pull-up resistors are used as pull-ups, and at no load, you get 5 volts. But, when loaded, the voltage will drop. However, if the current is kept within tolerance, the voltage should not fall below 2.0.