IC-DXC_11 Datasheet, PDF (9/11 Pages) IC-Haus GmbH – DIGITAL SENSOR I/O DRIVER

iC-DXC
DIGITAL SENSOR I/O DRIVER
CIRCUIT PROTECTION
preliminary
Rev A0.8, Page 9/11
The iC-DXC is reverse polarity protected via internal
circuitry. As far as the maximum voltage ratings are
not exceeded, no possible supply combination at the
line side pins (VB, GND and OUT) can damage the
chip.
Since the chip current consumption is relatively low,
discharging of the backup capacitor C1 can be very
slow, and injected charge through disturbances may
in general result in capacitor voltage exceeding maxi-
mum ratings, leading to malfunction or destruction of
circuitry and associated parts. Thus EMC require-
ments will afford more external circuitry. Figure 7
shows the iC-DXC with the additional protective device
D1, D2 and D3.
8
C3
100nF..
3
2
5
4
1 VOUT
REG
+
5V
-
VREF
<150 C
5 OE
DIGITAL INPUT
4 NIN
2 MON
6 CFO
&
&
iC-DXC
FILT
=1
High Side Switch
VB
8
7
C1
1μF
36V
36V
Low Side Switch
OUT
7
PSD36
D2
PSD36
D3
6
C2
1nF
D1
PSD36
GND 3
1
++ ^VRH
-
+ _VRL
EPAD
Figure 7: Circuit schematic showing protective devices
For over-voltage protection, the suppressor diodes
D1,D2 and D3 absorbs transients on supply line in-
jected externally on the cable. Clamp voltage of the
diodes should be rated slightly above maximum speci-
fied supply voltage.
These currents can be passed to ground or to VB
by the internal ESD diodes of the iC-DXC. Whereas
negative current injection will simply be drained off to
ground, positive current injection will charge capacitor
C1 further to higher voltages. If not suppressor diodes
nor any other over-voltage protection is implemented,
the backup capacitor C1 should be kept small. A typi-
cal 100nF value is normally OK.
Suggested protective devices
At VB_max of 36V, suppressor diodes with a breakdown
voltage from 36V has to be chosen in order to minimize
the energy in iC-DXC for higher Voltages. For example
Diode type like Vishay GSOT36C or PJSD36W from
Panjit should be enough as protection.