Document Number: 70064

S11-1029–Rev. H, 23-May-11

www.vishay.com

9

Vishay Siliconix

DG458, DG459

This document is subject to change without notice.

DETAILED DESCRIPTION

The Vishay Siliconix DG458 and DG459 multiplexers are

fully fault- and overvoltage-protected for continuous input

power supply pins (V+, V-). These multiplexers are built on a

high-voltage junction-isolated silicon-gate CMOS process.

Two n-channel and one p-channel MOSFETs are connected

in series to form each channel (Figure 1).

variation as a function of analog signal voltage is comparable

to that of the classic parallel N-MOS and P-MOS switches.

When the analog signal approaches or exceeds either

supply rail, even for an on-channel, one of the three series

MOSFETs gets cut-off, providing inherent protection against

overvoltages even if the multiplexer power supply voltages

are lost. This protection is good up to the breakdown voltage

of the respective series MOSFETs. Under fault conditions

only sub microamp leakage currents can flow in or out of the

multiplexer. This not only provides protection for the

multiplexer and succeeding circuitry, but it allows normal,

undisturbed operation of all other channels. Additionally, in

case of power loss to the multiplexer, the loading caused on

the transducers and signal sources is insignificant, therefore

redundant multiplexers can be used on critical applications

such as telemetry and avionics.

Vishay Siliconix maintains worldwide manufacturing capability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon Tech-

nology and Package Reliability represent a composite of all qualified locations. For related documents such as package/tape drawings, part marking, and reliability

Figure 5. Overvoltage Protection

- 15 V

- 15 V

+ 15 V

- 35 V

Overvoltage

+ 35 V

Overvoltage

n-Channel

MOSFET

is On

p-Channel

MOSFET

is Off

n-Channel

MOSFET

is Off

- 15 V

+ 15 V

D

S

G

D

S

G

D

S

G

- 35 V

Overvoltage

+ 35 V

Overvoltage

- 35 V

n-Channel

MOSFET

is On

p-Channel

MOSFET

is Off

n-Channel

MOSFET

is Off

(b) Overvoltage with Multiplexer Power On

(a) Overvoltage with Multiplexer Power Off