Datasheet

VBUS054B-HSF
www.vishay.com
Vishay Semiconductors
Rev. 1.9, 04-Jan-2019
6
Document Number: 81624
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
One mode of use is,…
in the very first moment before any pulses have arrived, all
three diodes are completely discharged (so the diode
capacitances are empty of charge) the first signal pulse with
an amplitude > 0.5 V will drive the upper PN-diode (D
1
) in a
forward direction and “sees” the empty capacitance of the
Z-diode (ZD).
Depending on the duration of this pulse and the pause to the
next one the Z-diodes capacitance can be charged up so
that the next pulse “sees” a lower capacitance. After some
pulses the big Z-diode could be completely charged up so
that the following pulses just see the small capacitance of
both PN-diodes.
For some application this can work perfectly.....




For others applications the capacitance must be the same
all the time from the first till the last pulse.

For these applications the appropriate mode of use is to
connect the Z-diode to the supply voltage.
In this mode the Z-diode is charged up immediately by the
supply voltage and both PN-diodes are always used in
reverse. This keeps their capacitance at a minimum.
20405
ZD
I/O
G
nd
D
1
D
2
ZD
I/O
G
nd
20406
V
BUS
D
1
D
2