Octal Channel Protectors
ADG467
FUNCTIONAL BLOCK DIAGRAM
VDD
Fault and overvoltage protection up to ±40 V
Signal paths open circuit with power off
Signal path resistance of RON with power on
44 V supply maximum ratings
Low on resistance: 62 Ω typical
±1 nA maximum path current leakage @ +25°C
Low RON match (5 Ω maximum)
Low power dissipation 0.8 μW typical
Latch-up proof construction
VSS
VD1
VD2
VIN
APPLICATIONS
ATE equipment
Sensitive measurement equipment
Hot insertion rack systems
VS2
VD3
VIN
VS1
VS3
VD8
VS8
ADG467
VDD
VOUT
VOUT
VDD
OUTPUT CLAMPED
AT VDD – 1.5V
08191-001
FEATURES
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.
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 approximately ±0.5 nA typical.
Each channel protector has an independent operation and consists 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, (VSS + 1.5 V) < VIN < (VDD − 1.5 V). When a channel’s analog
input exceeds the power supplies (including VDD and VSS = 0 V),
one of the MOSFETs switches off, clamping the output to either
VSS + 1.5 V or VDD − 1.5 V. Circuitry and signal source protection 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.
1.
The ADG467 can operate off both bipolar and unipolar
supplies. The channels are normally on when power is
The ADG467 is available in an 18-lead SOIC package and a
20-lead SSOP package.
PRODUCT HIGHLIGHTS
2.
3.
4.
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.
Low Power Dissipation.
Low RON. 62 Ω typical.
Trench Isolation Latch-Up Proof Construction.
A dielectric trench separates the p- and n-channel
MOSFETs thereby preventing latch-up.
Rev. B
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