DocID15255 Rev 2

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AN2859

Application example

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5

Application example

The third step is to calculate the window detection levels (see Table 5) according to

equations 5, 6, 7, 8, 9, 10, 11, 18, 19, 20, 21, 22, 23 and 24. The window detection digital

levels will be stored in the MCU firmware to distinguish the state of each AC switch.

Table 3. Defined values of the application

Symbol

Value

Unit

5mA

4.5

V

5.5

V

0V

1

V

N (MCU ADC resolution)

10

bits

Resistor settings

Standard value (5% tolerance)

2.2 k

Ω

15 k

Ω

6.8 k

Ω

Table 5. Detection window values

Windows detection level

Analog values (Volts)

Equivalent digital values

Max.

Min.

Max.

Min.

1.105

0

252

0

2.514

1.154

501

262

4.214

2.545

802

579

5.5

4.5

1024

> 802