Using As An Open Collector Output - Keysight VXI Bus 75000 C Series User And Programming Manual

Using as an Open Collector Output

Using as an Open Collector Output
The Keysight E1458A Digital I/O Module data lines can be used in an open
collector configuration. Connections for open collector require the use of
external power supplies and pull-up resistors. The internal pull-up mode of the
digital I/O module MUST be disabled for open collector output. Figure 3-2 shows
a single data line connection.
Figure 3-2 Typical Open Collector Data Line
The value of the pull-up resistor is calculated as follows:
The value of TTL High with the 200 ? pull-up resistor is calculated as follows:
Keysight E1458A 96-Channel Digital I/O Module User Guide
Vcc = 5.0 Vdc
Imax = IoutLow * safety_factor = 48 mA * 0.52 = 25 mA
R = Vcc / Imax = 5 / 0.025 = 200 Ohms
VHigh = Vcc * 6200 / (6200 + 200) = 4.84 Vdc
Using the Keysight E1458A Digital I/O Module
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