Page 2.3
32-CHANNEL DIGITAL I/O MODULE 40-412
pickering
SECTION 2 - TECHNICAL DESCRIPTION
When using the low side driver a similar effect occurs when the driver is opened. The inductive energy stored is
discharged
the voltage on the
out ut ecoming ositive and a clam diode
igure
acting to
rotect the driver It is recommended that the user fits a wheel diode
igure
to discharge the inductive
energ If a wheel diode is not fitted the
will clam the out ut at a voltage etween
and
relative
to the front panel ground, the voltage being dependent upon the breakdown voltage of D1, Figure 2.3.
Driving Capacitive Loads
The 40-412 can be used to drive capacitive loads. When the driver is closed, the current limit protection circuit will
limit the current owing into the ca acitive load ontinuous ra id connection and disconnection to a ca acitive load
may result in the thermal protection circuits preventing further operation. If this occurs, simply allow the 40-412 to
cool down, after which normal operation will resume.
Vext Connection
When using the high side drivers, Vext is required to provide the current to the 40-412 output circuits. The Vext
connection is made using multiple pins on the D-type connector. It is strongly recommended that if high load
currents are expected, then all the available pins are used to spread the current load in order to avoid damaging the
connector he connections to e t are internall linked together in the
so s ecific ins are not re uired to
be used for a particular bank of drivers. To maximize connector life we suggest using 5 Amps per pin or less. Users
should not a l negative voltages relative to ground to e t or a l voltages greater than
FP_GND Connection
When using the low side drivers, FP_GND is required to sink the current from the 40-412 output circuits. The FP_
GND connection is made using multiple pins on the D-type connector. It is strongly recommended that if high load
currents are expected, then all the available pins are used to spread the current load in order to avoid damaging
the connector he connections to P
are internall linked together in the
so s ecific ins are not
required to be used for a particular bank of drivers. To maximize connector life we suggest using 5 Amps per pin
or less. Spare FP_GND Connections can be used for the purpose of screening or shielding in cable assemblies or
connector blocks
Using High and Low Side Drivers
The user can select on an individual channel basis whether a high side or low side driver is used. In Figure 2.2, D3
prevents the discharge of energy into Vext when the low side driver is operated.
Low Side
Driver
Vext
FP_GND
En
40-412
GND
D1
D2
Output
C
Figure 2.3 - Using the 40-412: Driving an inductive load with a Low Side Driver
