Data Sheet ADG5462F
Rev. C | Page 27 of 29
APPLICATIONS INFORMATION
The overvoltage protected family of switches and multiplexers
provide robust solutions for instrumentation, industrial,
automotive, aerospace, and other harsh environments where
overvoltage signals can be present, and the system must remain
operational both during and after the overvoltage has occurred.
POWER SUPPLY RAILS
To guarantee correct operation of the device, 0.1 µF decoupling
capacitors are required on the primary and secondary supplies.
If they are driven from the same supply, then one set of 0.1 µF
decoupling capacitors is sufficient.
The secondary supplies (POSFV and NEGFV) provide the
current required to operate the fault protection and, therefore,
must be low impedance supplies. Therefore, they can be derived
from the primary supply by using a resistor divider and buffer.
The secondary supply rails (POSFV and NEGFV) must not exceed
the primary supply rails (VDD and VSS) because this can lead to a
signal passing through the switch unintentionally.
The ADG5462F can operate with bipolar supplies between ±5 V
and ±22 V. The supplies on VDD and VSS need not be symmetrical
but the VDD and VSS range must not exceed 44 V. The ADG5462F
can also operate with single supplies between 8 V and 44 V with
VSS connected to GND.
The ADG5462F is fully specified at ±15 V, ±20 V, +12 V, and
+36 V supply ranges.
POWER SUPPLY SEQUENCING PROTECTION
The channels remain open when the device is unpowered and
signals from −55 V to +55 V can be applied without damaging
the device. Only when the supplies are connected, and the signal
is within normal operating range, do the channels close. Placing
the ADG5462F between external connectors and sensitive
components offers protection in systems where a signal is
presented to the source pins (Sx) before the supply voltages
are available.
POWER SUPPLY RECOMMENDATIONS
Analog Devices, Inc., has a wide range of power management
products to meet the requirements of most high performance
signal chains.
An example of a bipolar power solution is shown in Figure 52.
The ADP7118 and ADP7182 can be used to generate clean
positive and negative rails from the dual switching regulator
output. These rails can power the ADG5462F, an amplifier,
and/or a precision converter in a typical signal chain.
12698-050
+15V
–15V
12V
INPUT ADP7182
LDO
DUAL
SWITCHING
REGULATOR
ADP7118
LDO
+16V
–16V
Figure 52. Bipolar Power Solution
Table 8. Recommended Power Management Devices
ADP7118 20 V, 200 mA, low noise, CMOS low dropout
regulator (LDO)
ADP7142 40 V, 200 mA, low noise, CMOS LDO
ADP7182 −28 V, −200 mA, low noise, linear regulator
USER DEFINED SIGNAL RANGE
The primary supplies define the on-resistance profile of the
channels, while the secondary supplies define the signal range.
Using voltages on POSFV and NEGFV that are lower than VDD
and VSS, the required signal can benefit from the flat on resistance
in the center of the full signal capabilities of the device.
LOW IMPEDANCE CHANNEL PROTECTION
The ADG5462F can be used as a protective element in signal
chains that are sensitive to both channel impedance and
overvoltage signals. Traditionally, series resistors are used to
limit the current during an overvoltage condition to protect
susceptible components.
These series resistors affect the performance of the signal chain
and reduce the precision that can be reached. A compromise
must be reached on the value of the series resistance that is high
enough to sufficiently protect sensitive components but low
enough that the precision performance of the signal chain is not
sacrificed.
The ADG5462F enables the designer to remove these resistors
and retain the precision performance without compromising
the protection of the circuit.
HIGH VOLTAGE SURGE SUPPRESSION
The ADG5462F is not intended for use in very high voltage
applications. The maximum operating voltage of the transistor
is 80 V. In applications where the inputs are likely to be subject
to overvoltages exceeding the breakdown voltage, use transient
voltage suppressors (TVSs) or similar.