IL300 schematic connections

[aggpankaj2]

Hi,

I need to use IL300, for insulation between one of my current sense feedback and MCU. I need only insulation and no amplification of signal. could you help me with schematic diagram for the same? My major concerns are:
1. Can i leave the K1 port unconnected?
2. Can the output from K2 port be directly given to MCU?
3. Resistor values and minimum components required?





Thanks.

 

[FvM]

It's not clear, how the shown circuit diagrams are related to your question. Both circuits share the same ground.

For the usage of IL300, you can refer to the reference circuit given in the datasheet. The specified performance can only be achieved by connecting one of the matched channels as feedback. Without the feedback, you can use the device like any standard optocoupler.

 

[aggpankaj2]

It's not clear, how the shown circuit diagrams are related to your question. Both circuits share the same ground.

For the usage of IL300, you can refer to the reference circuit given in the datasheet. The specified performance can only be achieved by connecting one of the matched channels as feedback. Without the feedback, you can use the device like any standard optocoupler.

The isolator has to be in between output current sense signal (shown in figure 1) and MCU (shown in figure 2). For feedback as you stated or to get 1:1 output do i need two extra OP-AMPs?

 

[FvM]

I only count one additional OP on the primary side. The secondary current to voltage conversion doesn't have to do with feedback operation. If you can work with a simple curresnt sense resistor in front of ADC, you don't need it.

 

[mister_rf]

Detalis also here:
**broken link removed**
Some schematics


As was mention before, you may skip using the IC3.

 

[aggpankaj2]

I only count one additional OP on the primary side. The secondary current to voltage conversion doesn't have to do with feedback operation. If you can work with a simple curresnt sense resistor in front of ADC, you don't need it.

There is actually a speculation, that large voltage spikes can occur on this signal because of some very high inductance/solenoids in design, so need to prevent MCU. If I need to create an isolation between this signal and MCU having 1:1 ratio, how do i do that?

---------- Post added at 08:20 ---------- Previous post was at 08:19 ----------

Detalis also here:
**broken link removed**
Some schematics


As was mention before, you may skip using the IC3.

no general circuit plz. circuit specific to my circuit will be helpful

 

[FvM]

If I need to create an isolation between this signal and MCU having 1:1 ratio, how do i do that?

Assuming 1.0 transfer gain, R2 and R3 would have equal values. The standard IL300 quality is however covering a range of 0.55 - 1.6, see order informations. An adjustment will be normally required.

You may want to check newer signal isolators that implement digital signal processing, available e.g. from Avagotech.

 

[aggpankaj2]

thanks everybody!!!