2MHz industrial isolated input ICs need only secondary-side power

Novosense Microelectronics has created a pair of isolated digital input chips suitable for 24V industrial control applications that only need power on the output side.

4-channel NSI8604 (SSOP16 package) and 8-channel NSI8608 (SSOP20) provide input/output isolation when converting voltages in the range of -60V to 60V to logic signals. (The third digit is a capital ‘i’, not a numerical ‘1’).

Data rate is from dc to 2Mbit/s with 380ns propagation delay.

“While compatible with the current input form of optocouplers, the chips provide for simplified system design thanks to a higher degree of system integration and the elimination of a need for a field-side power supply,” according to the company, which also said that they are “pin-compatible SI838x from Skyworks”.

They are second-source components, with an improvement.

Input current is limited to 2.1mA (typical) and the input side includes a rectifier (left) – Inputs are described by the company as “sinking or sourcing” and supporting “bi-directional digital functionality”. Novosense clarified to Electronics Weekly; “All channels share the same COM pin, so all inputs should be at same polarity simultaneously, either sourcing or sinking.”

If it is not current limiting, the inputs emulates an LED, dropping between 1.8 and 2.4V.

Operation is with a supply over 2.5 to 5.5V, and -40 to 125°C.

Inside, isolation is capacitive across a SiO₂ barrier using on-off keying (‘OOK modulation’).

Isolation is up to 3kVrms, and the company said CMTI (common-mode transient immunity) is both 35kV/μs, and 25kV/μs minimum.

“Each IC meets the performance criteria for switch types 1, 2 and 3 in IEC 61131-2, and is compatible with the I/O level of most microcontrollers,” said Novosense, although it also said “compliant to IEC 61131-2 Type 1, 3”.

Chip level ESD is ±4kV HBM (human body model).

UL recognition is 3kVrms (1min per UL1577), CQC certification is to GB4943.1-2011, they have CSA component notice SA approval (IEC60950-1) and DIN VDE V 0884-11:2017-01.

Applications are foreseen in PLCs (programmable logic controllers), servos and inverters.

Novosense is a analog and mixed signal IC company, founded in 2013 and based in Shanghai.

Editor’s note: Do excuse some vagaries above, the data sheet is not yet publically available for EW to fact-check against. Novosense has been contacted for clarification. The NSI860x product page can be found here. As an aside, all-electronic replacements for opto-isolators (and formerly opto-isolated: mosfet gate drivers and relay ICs) are appearing more frequently: Here are some notably innovative ones from TI.