DG408_06 Datasheet, PDF (8/17 Pages) Intersil Corporation – Single 8-Channel/Differential 4-Channel, CMOS Analog Multiplexers

DG408, DG409
Test Circuits and Waveforms (Continued)
5V +15V
V_IN
S_{1 EN V+}
SIGNAL
GENERATOR
V_O
D
A₂
A₁
R_L
A₀
V-
GND
-15V
ANALYZER
INSERTION LOSS = 20 Log ^{V-----O-----U-----T--}
VIN
3V OR 0V +15V
CHANNEL
SELECT
EN
A₂
A₁
V+
S₁
|
|
S₈
A₀
D
V-
GND
-15V
IMPEDANCE
ANALYZER
FIGURE 7. INSERTION LOSS
FIGURE 8. SOURCE/DRAIN CAPACITANCES
Typical Applications
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 9). 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 V+ - (V-) doesn’t
exceed 44V. The addition of these diodes will reduce the
analog signal range to 1V below V+ and 1V above V-, but it
preserves the low channel resistance and low leakage
characteristics.
Typical application information is for Design Aid Only, not
guaranteed and not subject to production testing.
V+
1N4148
S_X
V_G
D
DG408
1N4148
V-
FIGURE 9. OVERVOLTAGE PROTECTION USING BLOCKING
DIODES
8
FN3283.8
June 13, 2006