adc-44d ETC-unknow, adc-44d Datasheet - Page 25

• Manufacturer Part Number: adc-44d
• Description: Multi-function Analogue Input/output Card
• Manufacturer: ETC-unknow

Chapter 4
Analogue Current Outputs
Four current outputs are available corresponding to the four voltage outputs.
The outputs sink current from an external power supply provided by the user.
Additional pins are provided at the output connector to facilitate the external
wiring.
The current sinks 0 to 20mA through an external load. The output current
range of 0 to +20 mA corresponds to a voltage output of 0 to +10 Volts at the
equivalent voltage output pin. The output current is 0mA for a voltage output of
-10 Volts to 0 Volts.
The user must provide an external supply voltage for the current outputs. The
voltage for this supply should be +4 Volts minimum to +24 Volts maximum.
Selecting the Load Resistor/Supply Voltage
The output current drivers require an absolute minimum of 2 Volts at the output
terminals to function correctly. The value of load resistor in ohms for a given
supply voltage may be calculated from the following formula:
Load resistances less than the calculated value may be used.
To calculate the minimum supply voltage required for a known value of load
resistance, use the following equation:
Voltages in excess of the calculated minimum may be used up to the maximum
of 24 volts.
External voltages of less than 4 Volts, and external loads of less than 100 ohms
are not recommended.
Blue Chip Technology Ltd.
NOTE: Supplies greater than 24 Volts may cause serious damage to the
card.
R
V
supply
load
= [ V
= [ 0.02 x R
supply
- 2 ] x 50
load
I/O Connections
] + 2
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