DISTRIBUTION


Figure 5: Block diagram of the digital isolator CDIS 18012x15411x from Würth Elektronik.


Numerous EMC measures are also provided in the receiver section. The signal input from the twisted pair cable is equipped with transient protection and a common mode  from the cable. The power supplies around the DC/DC converters are equipped with   interference from outside and inside the  of the DC/DC converters. This ensures a high 


Capacitive digital isolators The digital isolator from Würth Elektronik [1,2] consists of an oscillator and a modulator on     


with an isolation barrier made of SiO2. The signal is transmitted across the isolation barrier using a modulation process known as   a Schmitt trigger. The modulator generates a differential signal that is transmitted across the capacitive isolation lines. Figure 4 shows the basic structure of a capacitive digital isolator. The demodulator,   reconstruction of the input signal. The signal   demodulator output to the overall output, 


8 Parameter Package


VIOSM - max. Surge Isolation voltage


Test


Error rate over the lifetime


IEC 60747-17 (VDE 0884-17)


Basic Isolation SOIC-8NB


5000 Vpk


VTEST = 1.3 x VIOSM VTEST = 6.5kV





required level. Figure 5 illustrates the internal structure.


Digital isolators are manufactured using   processes. The transmitter and receiver capacitors are mounted on a lead frame. The  4, are located between the two horizontal contacts shown in red. The dielectric material between the electrodes or capacitor plates serves as a galvanic isolation barrier.  process is in the range of a few tens of


micrometers. In digital isolators, SiO2 is used as the isolating material in the capacitor because its much higher dielectric strength of  less space for the isolating gap. Other common insulation materials, such as   connected with a bonding wire so that two capacitors are connected in series, as shown in the block circuit in Figure 4. To protect the entire structure, the die and leadframe


DECEMBER/JANUARY 2025 | ELECTRONICS FOR ENGINEERS


Reinforced Isolation SOIC-16WB


7070 Vpk


VTEST = 1.6 x VIOSM VTEST = 11.3kV





 process.


Reliability and safety


Digital isolators are designed to protect    the CDIP and CDIS series from Würth Elektronik  according to the latest and most demanding standard DIN EN IEC 60747-17 (VDE 0884- 17):2021-10 “Magnetic and capacitive couplers for basic insulation and reinforced insulation”. What do the terms “basic” and “reinforced”      “single fault condition” and “normal operating conditions”. Reinforced insulation provides protection against electric shock even under single-fault conditions in normal operation.  operation, i.e. without considering a single fault.


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