ADG466/ADG467

–7–

REV. 0

High Voltage Surge Suppression

The ADG466 and ADG467 are not intended for use in high

voltage applications like surge suppression. The ADG466

nected. When the power supplies are disconnected, the break-

down voltages on the input of the channel protector are

±35 V.

In applications where inputs are likely to be subject to overvolt-

ages exceeding the breakdown voltages quoted for the channel

protectors, transient voltage suppressors (TVSs) should be used.

These devices are commonly used to protect vulnerable circuits

from electric overstress such as that caused by electrostatic

discharge, inductive load switching and induced lightning. How-

ever, TVSs can have a substantial standby (leakage) current

(300

µA typ) at the reverse standoff voltage. The reverse standoff

voltage of a TVS is the normal peak operating voltage of the

circuit. Also TVS offer no protection against latch-up of sensitive

CMOS devices when the power supplies are off. The best solution

is to use a channel protector in conjunction with a TVS to provide

the best leakage current specification and circuit protection.

ADG466

ADC

TVSs

BREAKDOWN

VOLTAGE = 20V

Figure 14. High Voltage Protection

Figure 14 shows an input protection scheme that uses both a

TVS and channel protector. The TVS is selected with a reverse

standoff voltage that is much greater than operating voltage of

the circuit (TVSs with higher breakdown voltages tend to have

better standby leakage current specifications) but is inside the

breakdown voltage of the channel protector. This circuit pro-

tects the circuitry whether the power supplies are present

or not.

OBSOLETE