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X1/X2/Y1/Y2/Y4 impulse withstand rating voltage calculator (IEC 60384-14)
IEC 60384-14 specifies that X1/X2-rated capacitors shall be tested to withstand an impulse voltage of 4 kV (X1), 2.5 kV (X2, Y4), 8 kV (Y1) or 5 kV (Y2). However these values only apply for a...
View ArticleWhat is a transformer construction according to clause 19.12.3 of IEC 61558-1?
In transformer specifications or tests, you will often find sentences like Construction according to clause 19.12.3 of IEC 61558-1 This clause refers to isolated winding wire construction, i.e. a way...
View ArticleWhat is a transformer construction according to clause 26.2.4.1 of IEC 61558-1?
In transformer specifications or tests, you will often find sentences like Construction according to clause 26.2.4.1 of IEC 61558-1 This clause refers to hermetically sealed construction by...
View ArticleWhat is a SELV power supply?
SELV means Safety extra low voltage. This means that the voltage at the output of the power supply is so low that is isn’t considered a safety risk (less than 60V DC or 35VAC). the secondary side is...
View ArticleWhy do medical devices need 2xMOPP?
Also see: Does 2xMOOP / 2xMOPP require two separate converters / layers of isolation? For medical devices the IEC60601 norm specifies more stringent requirements for electrical safety like the 2xMOPP...
View ArticleWhat 1500pF 1kV capacitor should you use for Ethernet termination?
Nowadays you can use cheap ceramic capacitors for Ethernet termination. While they are not self-healing like foil capacitors, they work fine for all but the most demanding applications. Also, it’s...
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How should the SPI SCLK look on the oscilloscope?
SPI is typically used at 1-20MHz clock frequency. Start with setting the oscilloscope to 2 microseconds per division and 2V per division. Hence, set your scope. Set the trigger to edge mode to trigger...
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Diagnosing I2C issues using an oscilloscope: Slow rising edge, fast falling edge
If your I2C clock and/or data signal look like this: in other words, if the rising edge is very slow and not sharp compared to the you are facing an issue with a pull-up resistor which is too large. A...
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