AN729 データシートの表示（PDF） - Silicon Laboratories

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AN729

REPLACING TRADITIONAL OPTOCOUPLERS WITH Si87XX DIGITAL ISOLATORS

Silicon Laboratories 

AN729

4. Evaluation Board

The Si87xx package and pin-compatibility makes upgrading existing optocoupler circuits quick and easy. Simply

look-up the closest replacement to the incumbent optocoupler and replace the optocoupler with the appropriate

Si87xx (it may also be necessary to adjust the value of Anode input resistor RF for optimum operation). The PCB of

Figure 2 exercises an Si87xx digital isolator and a competing optocoupler simultaneously. The external digital input

signal is buffered and fed into the inputs of both devices while the output signals are observed on an oscilloscope.

Figure 3 shows the outputs of both devices at room temperature, while Figure 4 shows the outputs at 80 °C. Note

the faster propagation delay rise times provided by the Si87xx device.

Figure 2. Opto Comparison EVB

Figure 3. Optocoupler Comparison EVB at Room Temperature

4

Rev. 0.1

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