DG508A_MIL/509A_MIL

Vishay Siliconix

Document Number: 70067

S-00405—Rev. C, 21-Feb-00

www.vishay.com

S FaxBack 408-970-5600

5-9

TEST CIRCUITS

FIGURE 8. Insertion Loss

FIGURE 9. Source Drain Capacitance

1 k

W

D

Insertion Loss = 20 log

V+

GND

V–

–15 V

+15 V

EN

f = 1 MHz

D

EN

+15 V

–15 V

GND

V+

V–

Meter

HP4192A

Impedance

Analyzer

or Equivalent

Channel

Select

V+

Positive Supply

Voltage

(V)

V–

Negative Supply

Voltage

(V)

Logic Input Voltage

(V)

Analog Voltage

Range

(V)

15

10

12

–15

–12

–10

–8

2.4/0.8

2.4/0.8

2.4/0.6

2.4/0.4

–15 to 15

–12 to 12

–10 to 10

–8 to 8

Notes:

a.

Application Hints are for DESIGN AID ONLY, not guaranteed and not subject to production testing.

b.

Operation below

"8 V is not recommended.

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 11). 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

doesn’t exceed +44 V. The addition of these diodes will reduce

the analog signal range to 1 V below V+ and 1 V above V–, but

it preserves the low channel resistance and low leakage

characteristics.

1N4148

DG508A_MIL

D

–15 V

1N4148

V+

V–

+15 V

FIGURE 10. Overvoltage Protection Using Blocking Diodes

Internal

Junction

Internal

Junction