ADG5243F datasheet(28/30 Pages) AD

28 / 30 page

ADG5243F

Data Sheet

Rev. 0 | Page 28 of 30

APPLICATIONS INFORMATION

The overvoltage protected family of switches and multiplexers

provides 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, 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, thus, must

be low impedance supplies. Therefore, they can be derived from

the primary supplies 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 may

lead to a signal passing through the switch unintentionally.

The ADG5243F can operate with bipolar supplies between ±5 V

and ±22 V. The supplies on VDD and VSS need not be symmetrical,

but the VDD to VSS range must not exceed 44 V. The ADG5243F

can also operate with single supplies between 8 V and 44 V with

VSS connected to GND.

The ADG5243F device is fully specified at ±15 V, ±20 V, +12 V,

and +36 V supply ranges.

POWER SUPPLY SEQUENCING PROTECTION

The switch channel remains open when the device is unpowered

and signals from −55 V to +55 V can be applied without damaging

the device. The switch channel closes only when the supplies are

connected, a suitable digital control signal is placed on the control

pins, and the signal is within normal operating range. Placing the

ADG5243F between external connectors and sensitive components

offers protection in systems where a signal is presented to the

source pins before the supply voltages are available.

SIGNAL RANGE

The primary supplies define the on-resistance profile of the

channel, whereas 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.

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 51.

The ADP7118 and ADP7182 can be used to generate clean positive

and negative rails from the ADP5070 dual switching regulator

output. These rails can be used to power the ADG5243F, an

amplifier, and/or a precision converter in a typical signal chain.

LDO

+15V

–15V

12V

INPUT

ADP7182

LDO

ADP5070

ADP7118

+16V

–16V

Figure 51. Bipolar Power Solution

Table 10. Recommended Power Management Devices

Product

Description

ADP5070

1 A/0.6 A, dc-to-dc switching regulator with

independent positive and negative outputs

ADP7118

20 V, 200 mA, low noise, CMOS LDO

ADP7142

40 V, 200 mA, low noise, CMOS LDO

ADP7182

−28 V, −200 mA, low noise, linear regulator

HIGH VOLTAGE SURGE SUPPRESSION

The ADG5243F 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.

INTELLIGENT FAULT DETECTION

The ADG5243F digital output pin, FF, can interface with a

microprocessor or control system and can be used as an interrupt

flag. This feature provides real-time diagnostic information on

the state of the device and the system to which it connects.

The control system can use the digital interrupt, FF, to start a

variety of actions, as follows:



Initiating an investigation into the source of an overvoltage

fault.



Shutting down critical systems in response to the overvoltage

condition.



Using data recorders to mark data during these events as

unreliable or out of specification.

For systems that are sensitive during a start-up sequence, the

active low operation of the flag allows the system to ensure that

the ADG5243F is powered on and that all input voltages are

within the normal operating range before initiating operation.

The FF pin has a weak internal pull-up resistor, which allows

the signals to combine into a single interrupt for larger modules

that contain multiple devices.

The recovery time, tDIGREC, can be decreased from a typical 65 μs

to 900 ns by using a 1 kΩ pull-up resistor.

The specific fault digital output, SF decodes which inputs are

experiencing a fault condition. The SF pin reduces to below

0.4 V when a fault condition is detected on a specific pin,

depending on the state of the F0, F1, and F2 pins (see Table 9).

ADG5243F Datasheet(PDF) 28 Page - Analog Devices

ADG5243F Datasheet(HTML) 28 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Datasheet Download

Link URL