REV. A

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a

ADG465

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© Analog Devices, Inc., 1998

Single Channel Protector

in an SOT-23 Package

FUNCTIONAL BLOCK DIAGRAM

ADG465

OUTPUT CLAMPED

GENERAL DESCRIPTION

The ADG465 is a single channel protector in an SOT-23 pack-

age. The channel protector is placed in series with the signal

path, and will protect sensitive components from voltage tran-

sience in the signal path whether or not the power supplies are

present. Because the channel protection works regardless of the

presence of the supplies, the channel protectors are ideal for use

in applications where correct power sequencing cannot always

be guaranteed to protect analog inputs (e.g., hot-insertion rack

systems). This is discussed further, and some example circuits

are given, in the Applications section of this data sheet.

A channel protector consists of an n-channel MOSFET, a

p-channel MOSFET and an n-channel MOSFET, connected in

series. The channel protector behaves like a series resistor dur-

When a channel’s analog input exceeds the power supplies

Circuitry and signal source protection is provided in the event of

an overvoltage or power loss. The channel protectors can with-

stand overvoltage inputs from –40 V to +40 V. See the Circuit

Information section of this data sheet.

The ADG465 can operate from both bipolar and unipolar

supplies. The channels are normally on when power is con-

nected, and open circuit when power is disconnected. With

power supplies of

± 15 V, the on-resistance of the ADG465 is

80

Ω typ, with a leakage current of ± 1 nA max. When power

is disconnected, the input leakage current is approximately

± 5 nA typ.

The ADG465 is available in a 6-lead plastic surface mount

SOT-23 package, and an 8-lead

µSOIC package.

PRODUCT HIGHLIGHTS

1. Fault Protection.

The ADG465 can withstand continuous voltage inputs from

–40 V to +40 V. When a fault occurs due to the power sup-

plies being turned off, or due to an overvoltage being applied

to the ADG465, the output is clamped. When power is turned

off, current is limited to the nanoampere level.

2. Low Power Dissipation.

4. Trench Isolation Latchup-Proof Construction.

A dielectric trench separates the p- and n-channel MOSFETs

thereby preventing latchup.

FEATURES

Fault and Overvoltage Protection up to

40 V

Signal Paths Open Circuit with Power Off

44 V Supply Maximum Ratings

Low On Resistance 80

Typ

1 nA Max Path Current Leakage @ +25 C

Low Power Dissipation 0.8

W Typ

Latchup-Proof Construction

APPLICATIONS

ATE Equipment

Sensitive Measurement Equipment

Hot-Insertion Rack Systems

ADC Input Channel Protection