Precision, CMOS Analog Switches
MAX317/MAX318/MAX319
_______________________________________________________________________Pin Description
PIN
MAX317
1
2
—
3
4
5
6
7
8
—
MAX318
1
2
—
3
4
5
6
7
—
8
MAX319
1
—
8
3
4
5
6
7
2
—
NAME
COM
N.C.
NO
GND
V+
VL
IN
V-
NC
NO
FUNCTION
Analog-switch common terminal
No connect — not internally connected
Analog-switch normally open terminal
Logic ground
Analog-signal positive supply input
Logic-level positive supply input
Logic-level input
Analog-signal negative supply input
Analog-switch normally closed terminal
Analog-switch normally open terminal
__________Applications Information
Operation with Supply Voltages
Other Than ±15V
The main limitation of supply voltages other than ±15V
is analog signal range reduction. The MAX317/
MAX318/MAX319 switches operate with bipolar sup-
plies of ±5V to ±20V. Typical Operating Characteristics
graphs show typical on resistance for ±15V, ±10V, and
±5V supplies. Switching times increase by a factor of
two or more for operation at ±5V. The
MAX317/MAX318/MAX319 can operate from unipolar
supplies of +10V to +30V. Both parts can also operate
from unbalanced supplies such as +24V and -5V.
Connect V- to 0V when operating with a single supply.
This means that VL must be connected to +5V to be
TTL compatible, or to V+ for CMOS logic input levels.
adding two small signal diodes in series with the sup-
ply pins (Figure 1). Adding the diodes reduces the
analog signal range to 1V below V+ and 1V below V-,
but low switch resistance and low leakage characteris-
tics are unaffected. Device operation is unchanged,
and the difference between V+ to V- should not exceed
+44V.
V+
V+
NO_
COM_
Vg
Overvoltage Protection
Proper power-supply sequencing is recommended for
all CMOS devices. It is important not to exceed the
absolute maximum ratings because stresses beyond
the listed ratings 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
possible, protect the devices from overvoltage by
V-
V-
Figure 1. Overvoltage Protection Using Blocking Diodes
6
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