ISO7421

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ISO7420, ISO7420M, ISO7421

SLLS984I – JUNE 2009 – REVISED JULY 2015

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9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

9.1 Application Information

ISO742x utilize single-ended TTL-logic switching technology. Its supply voltage range is from 3.15 V to 5.25 V for

single-ended design structure, digital isolators do not conform to any specific interface standard and are only

intended for isolating single-ended CMOS or TTL digital signal lines. The isolator is typically placed between the

data controller (i.e.

μC or UART), and a data converter or a line transceiver, regardless of the interface type or

standard.

9.2 Typical Application

ISO7421 can be used with Texas Instruments' mixed signal micro-controller, digital-to-analog converter,

transformer driver, and voltage regulator to create an isolated 4-20 mA current loop.

Figure 12. Isolated 4-20 mA Current Loop

9.2.1 Design Requirements

Unlike optocouplers, which require external components to improve performance, provide bias, or limit current,

the ISO742x only require two external bypass capacitors to operate.

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Product Folder Links: ISO7420 ISO7420M ISO7421