User`s manual

32 Operation Theorem
Figure 4-2: Differential Input circuits of cPCI-7230
4.2 Isolated Digital Output Circuits
On the 7230/7234 series, an external voltage source, minimum
5V, maximum 35 VDC, is necessary to power the internal isolated
circuits. It is connected with the VDD pin, When the isolated digital
output goes to high, the sink current will be from VDD.
On the 7230/7234 series, the VDD pin is used as a “fly-wheel”
diode, which can protect the driver if the loading is inductance
loading such as relay, motor, or solenoid.
The VDD must connect to the external power to form a fly-wheel
current loop.
1.2K Ohm
DI_nH
DI_nL