Applications Information
Operation with
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 ±20V 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 +24V and
-5V. The
Typical Operating Characteristics
graphs
show typical on-resistance with 20V, 15V, 10V, and 5V
supplies. (Switching times increase by a factor of two or
more for operation at 5V.)
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.
DG408/DG409
Improved, 8-Channel/Dual 4-Channel,
CMOS Analog Multiplexers
6 _______________________________________________________________________________________
______________________________________________________________Pin Description
Figure 1. Overvoltage Protection Using External Blocking
Diodes
PIN
DG408 DG409
NAME FUNCTION
1, 15, 16 A0, A2, A1 Address Inputs
—
—
A0, A1 Address Inputs
2 2 EN Enable Input
3 3 V- Negative Supply Voltage Input
4–7 — S1–S4 Bidirectional Analog Inputs
— 4–7 S1A–S4A Bidirectional Analog Inputs
8 — D Bidirectional Analog Output
— 8, 9 DA, DB Bidirectional Analog Outputs
9–12 — S8–S5 Bidirectional Analog Inputs
— 10–13 S4B–S1B Bidirectional Analog Inputs
13 14 V+ Positive Supply Voltage Input
14 15 GND Ground
1, 16