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Replace optical isolator with digital isolator?

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Member level 4
Mar 16, 2017
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I have an H bridge, all transistors are controlled by high current integrated drivers and are fully isolated and controlled by a fast-speed optocoupler ACPL-P484.
The switching frequency of the bridge is relatively high up to 400kHz.
The isolator does not switch any large capacitances, only the parasitic capacitance of the logic input IC, PCB and Pul Up / Down resistor with a current in the order of tens of uA. Vcc 5V

I would like to replace 4 pieces of optoisolators with one piece of digital isolator, for example ISO676x.

At first glance, I do not see a problem in the change, the digital isolator seems to be faster. It is assumed that the 4 channels in one case will be even more subdued than in the four cases.
The first look may not be correct, so I ask, isn't there a problem with a similar upgrade?

Digital is way faster than most optos especially older photo-BJT types. But there are big differences in isolation-ruggedness between an optical slab and the coupling schemes used in digital isolators (capacitive is especially suspicious in my mind), the digital couplers will refer to an industry spec as if it answers your "abnormal conditions" the real product may impose but must survive. But it really means that -you- must understand, prove and make that call.

Old times optos were general purpose and simple. They (many of them) can take a higher voltage in fact than the new styles, which are tailored to application and market demand.

Beware the common-mode transient immunity dV/dt rating if your high side switches fast and hard at highest load.

I might suggest scrubbing selection guides for various types against each other with a particular eye to what one guy says and another fails to mention (except in some non-obvious app note or the 19th page of the datasheet). Bury the bad news, like.

TI with a capacitive insulation barrier manufactures the Gate Driver for exmple UCC21530. I might use them, but they are completely unavailable at the moment and I need an external Bootstrap Circuit.

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