DG408/409
Vishay Siliconix
APPLICATIONS HINTS
Overvoltage Protection
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 10). 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
V+
becomes the power supply of the IC. From the point of view
of the chip, nothing has changed, as long as the difference
VS - (V-) 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.
1N4148
S
X
D
V
g
DG408
1N4148
V-
Figure 10. Overvoltage Protection Using Blocking Diodes
8-Channel Sequential Multiplexer/Demultiplexer
+ 15 V
- 15 V
Differential 4-Channel Sequential Multiplexer/Demultiplexer
+ 15 V
- 15 V
V+
S
1
S
2
S
3
Analog
Inputs
(Outputs)
S
4
S
5
S
6
S
7
S
8
A
0
GND
V-
Analog
Output
(Input)
V+
S
1a
S
2a
Differential
Analog
Inputs
(Outputs)
S
3a
S
4a
GND
V-
D
a
DG408
D
DG409
S
1b
S
2b
S
3b
S
4b
A
0
D
b
Differential
Analog
Outputs
(Inputs)
+ 15 V
A
1
A
2
EN
+ 15 V
A
1
EN
Clock
In
NC
DM7493
B
IN
A
IN
r
01
Q
B
Q
C
Q
D
J
Q
1/2 MM74C73
CLK
K
Q
GND
NC
J
Q
1/2 MM74C73
CLK
K
CLEAR
6
Q
NC
Q
A
r
02
GND
NC
Clock
In
+ 15 V
Enable In
(MUX On-Off Control)
Reset Enable
CLEAR
Figure 11.
Vishay Siliconix maintains worldwide manufacturing capability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon
Technology and Package Reliability represent a composite of all qualified locations. For related documents such as package/tape drawings, part marking, and
reliability data, see
http://www.vishay.com/ppg?70062.
Document Number: 70062
S-71155–Rev. G, 11-Jun-07
www.vishay.com
11
VISHAY [ VISHAY TELEFUNKEN ]
