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13/28
Bosch Rexroth AG
Information on this product
Voltage and current profile
Current
I
A
I
H
I
L
On
If voltage is applied to both switching inputs "IN1" and "IN2" (2), which is greater
than / equal to the switch-on threshold, the output stage is activated.
If voltage is applied to both switching inputs "IN1" and "IN2" (2), which is greater
generator (3)
than / equal to the switch-on threshold, the voltage and current profile generator
will create an internal control signal for the output stage (4). This signal will be
used by the output stage (4) for the generation of a voltage/current profile for the
overexcitation of the valve solenoid (terminal 7 and 8).
Output stage (4)
If voltage is applied to both switching inputs "IN1" and "IN2" (2), which is greater
than / equal to the switch-on threshold, the output stage is activated. By means of
the voltage and current profile generator (3), the output stage generates a volt-
age/current profile (see figure 2) at the valve solenoid (terminal 7 and 8), which
leads to overexcitation of the solenoid. This overexcitation allows for considerably
reduced switching times of the valve.
Boost
Pull-in
phase t
phase t
B
A
Current in the solenoid coil of the on/off valve
Current in the module amplifier supply line
Fig. 2: Current profile of the VT-MSFA1
The output stage outputs (terminals 7 and 8) are protected against reversed po-
larity and short-circuit. Apart from that, the output stage will be de-energized if one
of the two switching signals "IN1" or "IN2" is missing or if a fault is identified.
In order to ensure fast shut-down of the valve, no free-wheeling diode must be
connected to the solenoid of the on/off valve!
VT-MSFA1 | RE 30260-B/07.12
I
= Pull-in current
A
I
= Holding current
H
I
= Charging current
L
Holding phase
Loading phase t
L
Fast shut-down
Time t
Off
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