3

2

1

0

2

3

4

5

VDD1 (V)

1

0

5.5

4.5

2.5

3.5

1.5

0.5

VFAILSAFEmax

3.5

2.5

1.5

0.5

Outputs are not specified

in this VDD1 range

21

ISO224

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SBAS738A – JUNE 2018 – REVISED OCTOBER 2018

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Feature Description (continued)

8.3.4 Fail-Safe Output

The ISO224 offers a fail-safe output that simplifies diagnostics on system level. The fail-safe output is active

when the high-side power supply VDD1 of the device is missing, independent of the input signal at the IN pin.

Figure 46 shows that in that case both outputs, OUTP and OUTN, of the device are actively driven close to

GND2 (see the VFAILSAFE specification in the Electrical Characteristics table for details). For easy visualization, an

example with the input signal VIN = 0 V is shown for the valid VDD1 range of 4.5 V to 5.5 V.

Figure 46. ISO224 Failsafe Output Behavior With VIN = 0 V

The ISO224 Fail-Safe Output Feature application report describes an example of a comparator-based circuit that

detects the missing high-side supply in a system.

8.4 Device Functional Modes

The ISO224 is operational when the power supplies VDD1 and VDD2 are applied, as specified in the

Recommended Operating Conditions table.