DG508A_MIL/509A_MIL
Vishay Siliconix
TEST CIRCUITS
+15 V
+15 V
V
S
R
g
= 50
W
S
1
V+
A
2
V+
S
1
Meter
S
8
HP4192A
Impedance
Analyzer
or Equivalent
f = 1 MHz
A
0
A
1
A
2
GND
EN
V–
–15 V
D
R
L
1 kW
V
O
Channel
Select
A
1
A
0
D
GND
EN
V–
–15 V
Insertion Loss = 20 log
V
OUT
V
IN
FIGURE 8.
Insertion Loss
FIGURE 9.
Source Drain Capacitance
APPLICATIONS
a
V+
Positive Supply
Voltage
(V)
15
10
12
8
b
V–
Negative Supply
Voltage
(V)
–15
–12
–10
–8
V
IN
Logic Input Voltage
V
INH(min)
/V
INL(max)
(V)
2.4/0.8
2.4/0.8
2.4/0.6
2.4/0.4
V
S
or V
D
Analog Voltage
Range
(V)
–15 to 15
–12 to 12
–10 to 10
–8 to 8
Notes:
a. Application Hints are for DESIGN AID ONLY, not guaranteed and not subject to production testing.
b. Operation below
"8
V is not recommended.
Overvoltage Protection
V+ v V
g
v V–
+15 V
1N4148
V+
A very convenient form of overvoltage protection consists of
adding two small signal diodes (1N4148, 1N914 type) in series
with the supply pins (see Figure 11). This arrangement
effectively blocks the flow of reverse currents. It also floats the
supply pin above or below the normal V+ or V– value. In this
case the overvoltage signal actually becomes the power
supply of the IC. From the point of view of the chip, nothing has
changed, as long as the difference between V
S
and the V– rail
doesn’t exceed +44 V. The addition of these diodes will reduce
the analog signal range to 1 V below V+ and 1 V above V–, but
it preserves the low channel resistance and low leakage
characteristics.
DG508A_MIL
Internal
Junction
S
X
V
g
Internal
Junction
D
V–
1N4148
–15 V
FIGURE 10.
Overvoltage Protection Using Blocking Diodes
Document Number: 70067
S-00405—Rev. C, 21-Feb-00
www.vishay.com
S
FaxBack 408-970-5600
5-9
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