Octal Channel Protectors
ADG467
Rev. B
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FEATURES
Fault and overvoltage protection up to ±40 V
Signal paths open circuit with power off
Signal path resistance of R
ON
with power on
44 V supply maximum ratings
Low on resistance: 62 Ω typical
±1 nA maximum path current leakage @ +25°C
Low R
ON
match (5 Ω maximum)
Low power dissipation 0.8 μW typical
Latch-up proof construction
APPLICATIONS
ATE equipment
Sensitive measurement equipment
Hot insertion rack systems
FUNCTIONAL BLOCK DIAGRAM
08191-001
V
IN
V
OUT
V
DD
V
DD
OUTPUT CLAMPED
AT V
DD
– 1.5V
ADG467
V
D1
DD
SS
V
D2
V
D3
V
D8
V
S1
V
S2
V
S3
V
S8
V
IN
V
OUT
Figure 1.
GENERAL DESCRIPTION
The ADG467 is an octal channel protector. The channel
protector is placed in series with the signal path. The channel
protector protects sensitive components from voltage transience
in the signal path regardless if the power supplies are present or
not. For this reason, the channel protectors are ideal for use in
applications where correct power sequencing cannot always be
guaranteed (for example, hot insertion rack systems) to protect
analog inputs. This is described further, and some example
circuits are given in the Applications Information section.
Each channel protector has an independent operation and con-
sists of an N-channel MOSFET, a P-channel MOSFET, and an
N-channel MOSFET, connected in series. The channel protector
behaves just like a series resistor during normal operation, that
is, (V
SS
+ 1.5 V) < V
IN
< (V
DD
− 1.5 V). When a channel’s analog
input exceeds the power supplies (including V
DD
and V
SS
= 0 V),
one of the MOSFETs switches off, clamping the output to either
V
SS
+ 1.5 V or V
DD
− 1.5 V. Circuitry and signal source protec-
tion is provided in the event of an overvoltage or power loss.
The channel protectors can withstand overvoltage inputs from
−40 V to +40 V. See the Circuit Information section.
The ADG467 can operate off both bipolar and unipolar
supplies. The channels are normally on when power is
connected and open circuit when power is disconnected. With
power supplies of ±15 V, the on resistance of the ADG467 is
62 Ω typical with a leakage current of ±1 nA maximum. When
power is disconnected, the input leakage current is approx-
imately ±0.5 nA typical.
The ADG467 is available in an 18-lead SOIC package and a
20-lead SSOP package.
PRODUCT HIGHLIGHTS
1. Fault Protection.
The ADG467 can withstand continuous voltage inputs
from −40 V to +40 V. When a fault occurs due to the
power supplies being turned off or due to an overvoltage
being applied to the ADG467, the output is clamped.
When power is turned off, current is limited to the
microampere level.
2. Low Power Dissipation.
3. Low R
ON
. 62 Ω typical.
4. Trench Isolation Latch-Up Proof Construction.
A dielectric trench separates the p- and n-channel
MOSFETs thereby preventing latch-up.
