Improved, 8-Channel/Dual 4-Channel,
CMOS Analog Multiplexers
______________________________________________________________Pin Description
PIN
NAME
FUNCTION
DG408
DG409
—
1, 15, 16
A0, Aꢀ, A1
A0, A1
ꢁN
Address Inputs
Address Inputs
ꢁnable Input
—
ꢀ
1, 16
ꢀ
3
3
V-
Negative Supply Voltage Input
Bidirectional Analog Inputs
Bidirectional Analog Inputs
Bidirectional Analog Output
Bidirectional Analog Outputs
Bidirectional Analog Inputs
Bidirectional Analog Inputs
Positive Supply Voltage Input
Ground
4–7
—
—
S1–S4
S1A–S4A
D
4–7
—
8/DG409
8
—
8, 9
—
DA, DB
S8–S5
S4B–S1B
V+
9–1ꢀ
—
10–13
14
13
14
15
GND
Applications Information
V+
Operation with
DG408
DG409
Supply Voltages Other than 15V
Using supply voltages less than 15V reduces the ana-
log signal range. The DG408/DG409 switches operate
with 5V to ꢀ0V bipolar supplies or with a +5V to
+40V single supply. Connect V- to GND when operat-
ing with a single supply. Both device types can also
operate with unbalanced supplies, such as +ꢀ4V and
-5V. The Typical Operating Characteristics graphs
show typical on-resistance with ꢀ0V, 15V, 10V, and 5V
supplies. (Switching times increase by a factor of two or
more for operation at 5V.)
S
D
V
g
Overvoltage Protection
Proper power-supply sequencing is recommended for
all CMOS devices. Do not exceed the absolute maxi-
mum ratings, because stresses beyond the listed rat-
ings may cause permanent damage to the devices.
Always sequence V+ on first, then V-, followed by the
logic inputs, S or D. If power-supply sequencing is not
possible, add two small signal diodes in series with
supply pins for overvoltage protection (Figure 1).
Adding diodes reduces the analog signal range to 1V
below V+ and 1V above V-, but does not affect the
devices’ low switch resistance and low leakage charac-
teristics. Device operation is unchanged, and the differ-
ence between V+ and V- should not exceed +44V.
V-
Figure 1. Overvoltage Protection Using ꢁxternal Blocking
Diodes
6
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