If the supply voltage to the DCDC converter is 12V converting to in and isolated to 3.3V

how to configure to drive input of isolators at 3.3 V

Hello everyone,

I am totally new to this forum looking for a help. Any tips and advice regarding my issue would be appreciated. I am jacksonlevi, working in a Corporate animation Company. I wanted to know that could the VDDA and GNDA actually be configured such that if, for example, a +15V/-5V bi-polar type biasing be fed into the chip and the source/emitter return of the device connected to separate neutral point?Or a different way could be that a 20V supply be placed between those pins, then using a secondary zener diode with resistors and capacitors create a +15V/-5V gate biasing ckt w/ a derived, floating source/emitter return point.Is there anything in the chip itself that would prevent negative biasing or reverse current flow? I have serached for this issue but did not find any right solution. Please help me

Any help would be greatly appreciated!!

Thank you.

Hi,

When I checked the figure 3.1 on the data sheet, I have realized ( or I am fooling myself) that the connection of the nmos is in the wrong direction. The source pin of the Si8751 is connected to the drain of the mos. 

is there anybody can please clarify this for me ?

Thanks in advance

Best

Hi, do we have the design guide for Si8834x Vin 3.0 V – 5.5 V to Vout 24 V. the AN892: Design Guide for Isolated DC-DC Using the Si882xx/883xx seems do not cover for the Vout to 24V in the design schematic. 

Hi,

Refer to AN1050 pdf file. I modified some components(V3, L2, L1), because of the PCB size is not big enough.

When I power up the circuit(Rload = 2.5ohm) through PSE device, Vout do not have output voltage. 

Is this because I tied VSSA to GND in my design? or the components I modified make the circuit loop unstable？

Best regards,

Chris Cao

Hi!

I am currently looking for a programming buffer.

This is doesn't have the exact functionality as i2c, but I am using these data lines:

TDO (output from MCU), SWCLK (input to MCU), SWDIO (input and output), reset pin (input and output).

I was wondering if it was possible to send data through the designated clock pin on this IC or does it have to buffer the clock signal at this designated pin?

Hello

I'm using Si3402B for PoE function.

How about hot swap availability of Si3402B.

It should be available, but I could not confirm some documentations.

BR

Hi,

I'm currently using optoisolator(MOCD207M) for charge enable of my design. 

PIN1- ANODE 1: 3.3V

+470ohm serial resistors

PIN2-GND_A

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? 

 

Shortly,

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?

Thank you.

Hi 

I have some 24V inputs, but I have no requirement of being compatible with IEC61131-2 standard.
I had a look at the application note AN970 on how to calculate resistor values for Si838x input networks.

What I wonder is: What is the exact purpose of the low-side resistor (R1)?

When using a traditional optocoupler, I would just use a resistor in series with the led (R2) to limit the forward current, without a resistor parallel to the led (R1). So I wonder, would the Si838x emulated led input behave the same way as a real led when using without a low-side resistor, or would the forward voltage (VF) go up to 24V and damage the device?

Thanks for any feedback
Simon

From the datasheet the SDO output pin should enter high-Z when EN is high.  I have tried 3 different chips, and all of them have high SDO pin.  Exept of this, the SPI communication is ok.  VDDA and VDDB is +3V3.  Any suggestions? 

As shown in the schematic diagram, the input signals A1 and B2 of SI8621 are normal square waves, but the waveforms of output B1 and A2 are like oscillograph waveforms, which show irregular waveforms and ripple. After testing, it is found that there are ripple waves in power supply 5.1v. Please help confirm whether there are problems with the schematic diagram and PCB board layout.thank you!

As shown in the schematic diagram, the input signals A1 and B2 of SI8621 are normal square waves, but the waveforms of output B1 and A2 are like oscillograph waveforms, which show irregular waveforms and ripple. After testing, it is found that there are ripple waves in power supply 5.1v. Please help confirm whether there are problems with the schematic diagram and PCB board layout.thank you!

Hello Community,

I am using a SI8380PF in an inverter for galvanic isolation of the control signals. My customer encountered sporadic delays when turning off: The input signal changes from High to Low and the isolated output signal remains High for 100 milli sec. The delay occurs at irregular intervals.

The application is time-sensitive and a delay of 100 ms is above the acceptable level. The circuitry around is 100% in accordance with AN970 and the datasheet.

Is the delay caused by the debounce-circuit? Could this problem be avoided when using SI8380P (same IC with 0ms low pass filter delay)?

Thanks in advance and best regards,

Alex

I am upgrading a system that uses mixed HCPL 2611 and HCPL 2612 and want to go to one digital isolator.  Input currents range from 5mA up to 22mA.  Can this be done with an Si87xx part?