
DG421/DG423/DG425
Improved Low-Power,
CMOS Analog Switches with Latches
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5
___________________Pin Descriptions
1, 8
D1, D2
Drain Terminals
2
–
W
–
—
–
R
–
Write Select
3, 4, 5, 6
N.C.
No Internal Connection
7
–
R
–
—
–
S
–
Reset Select
9, 16
S1, S2
Source Terminals
10, 15
IN1, IN2
Input Control
11
V+
Positive Supply
12
VL
Logic Supply
13
GND
Ground
14
V-
Negative Supply
1, 8, 3, 6
2, 10, 4, 8
Drain Terminals
2
3
Write Select
–
W
–
—
–
R
–
16, 9, 4, 5 20, 12, 5, 7
Source Terminals
S1-S4
7
9
Resets Select
D1-D4
15, 10
19, 13
Input Control
IN1, IN2
11
14
Positive Supply
V+
–
R
–
—
–
S
–
12
15
Logic Supply
VL
—
1, 6, 11, 16
No Internal Connection
N.C.
14
18
Negative Supply
V-
13
17
Ground
GND
PIN
NAME
FUNCTION
DIP
PLCC
FUNCTION
NAME
Figure 1. Overvoltage Protection Using External Blocking Diodes
__________Applications Information
Operation with Supply Voltages
Other Than ±15V
The DG421/DG423/DG425 switches operate with ±4.5V
to ±20V bipolar supplies or with a +10V to +30V single
supply. In either case, analog signals ranging from V+
to V- can be switched. The
Typical Operating
Characteristics graphs illustrate typical analog-signal
and supply-voltage on-resistance variations. The usual
on-resistance temperature coefficient is 0.5%/°C (typ).
Logic Inputs
These devices operate with a single positive supply or
with bipolar supplies. They maintain TTL compatibility
with supplies anywhere in the ±4.5V to ±20V range as
long as VL = +5V. If VL is connected to V+ or another
supply at voltages other than +5V, the devices will
operate at CMOS-logic-level inputs.
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, followed by VL, V-, and
logic inputs. If power-supply sequencing is not possi-
ble, add two small, external 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-, without affecting low switch
resistance and low leakage characteristics. Device
operation is unchanged, and the difference between V+
and V- should not exceed +44V.
V+
D
V-
S
Vg
DG421
DG423/DG425