I'm currently using optoisolator(MOCD207M) for charge enable of my design.
PIN1- ANODE 1: 3.3V
+470ohm serial resistors
PIN8-COLLECTOR 1: Pin of IC
PIN9-EMITTER 1: GND_B
The pin of IC goes to LOW for charge enable.
If it is possible, I would like to use SI8620 instead of optoisolator.
Is there any problem for my application?
1)There are basic circuit right now with optocoupler as I said. 3.3V supply to ANODE 1 and ANODE 2 (with 470ohm serial resistors for 7mA).
The pin of the IC-1 is in COLLECTOR-1. The pin of the IC-2 is in COLLECTOR-2. (grounds seperately)
When we want to bring the pin of the ICs to ground (this meaning charge enable), we supply a 3.3V supply voltage to ANODE-1 and ANODE-2 together. It's for switching.
Can I make this switch with ISO7720?
2) Should I use Si8620BB-B-IS (Default Output LOW) or Si8620EB-B-IS (Default Output HIGH) for this switching? Which one is okey for my application? Is there any reference design like optocoupler?
3) Should I use 2 isolated supply for Vcc1 and Vcc2 ? But I have to use only 1 supply(3.3V) for that and for switching. Is it possible?
4) Do you have any other recommend for my application?
There are a couple of things you would need to consider when switching to either the Si8620 or the ISO7720. The first thing to consider is that neither the Silicon Labs part nor the TI part have LED inputs. They both expect a standard digital input.
The second thing to consider is that you are currently using an inverted logic: driving the input high causes your output to go low. Neither the Silicon Labs part nor the TI part will do that for you directly. You will need to take care of that yourselves.
To answer your direct questions:
1) You should be able to make either the Si8620 or the ISO7720 to work. Of course, I recommend the Si8620.
2) Which option you use, default low or default high, depends on how you want your device to perform should the input supply fail. If your charging circuit enables charging when the output is low, you would probably want the device to default high if there is a fault. But that is just a guess on my part.
3) The Si8620 is designed for applications that require the input and output supplies be isolated from one another. However, this is not a requirement for the part. You absolutely can provide the same supply to both the input and the output of the Si8620.
4) If you prefer an LED input, Silicon Labs also offers a family of digital isolators with an LED emulator input. These devices have an input that electrically behaves like an LED so you can drive it just like you are driving the opto-isolator currently. These are the Si87xx family. You can find information here: https://www.silabs.com/products/isolation/digital-isolators/si87xx-digital-isolators
These devices even have an open collector output like your isolator currently provides. With this you wouldn't have to change the logic of your application. You could still drive 3.3V to the anode and the output will pull low to enable charging.
I hope this is helpful. If you have any other questions, please feel free to ask.