DG408, DG409
Vishay Siliconix
APPLICATION 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 becomes the power
V+
supply of the IC. From the point of view of the chip, nothing
has changed, as long as the difference VS - (V-) does not
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-
Fig. 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
Fig. 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
www.vishay.com/ppg?70062.
Document Number: 70062
S11-0933-Rev. J, 16-May-11
www.vishay.com
11
This document is subject to change without notice.
THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT
www.vishay.com/doc?91000
VISHAY [ VISHAY TELEFUNKEN ]
