24
•
Operation Theorem
1 . 2 K O h m
D I _ n H
D I _ n L
Figure 3.2 Differential Input circuits of cPCI-7233
4.2 Isolated Digital Output Circuits
The connection of isolated digital output is shown as following diagram. The
PCI-7230 need external 10~30V DC power from the VDD pin to provide the
power source of the digital output circuit. The cPCI-7230 and PCI-7234 is
equipped with internal DC-DC converter.
On PCI-7230, an external voltage source, minimum 10V, maximum 35 VDC, is
necessary to power the internal isolated circuits. It is connected with pin-19 of
CN2, When the isolated digital output goes to high, the sink current will be from
VDD.
On PCI-7234 and cPCI-7230, the VDD pin is used as “fly-wheel” diode, which
can protect the driver if the loading is inductance loading such as relay, motor
or solenoid.
You can use the following wiring diagram. The VDD must connect to the
external power to form a fly-wheel current loop.
DC (5-35V)
+
Load
V
DD
IDO
n
EOGND
PC 817
Darlington
Sink Driver
V5V
DC (5-35V)
+
