Folks,

I'm looking to isolate analogue and digital circuits with very low frequency signals - switches in fact. The Si8380 looks like it will potentially do the trick. I've used TI's digital isolators before and simply connected pins directly to other devices. So, for example, from a micro to an input pin of the isolator and an output pin directly to its destination device.

I'm not at all clear - and maybe I'm just being numb - whether I night need a series resistor from a micro to the input of the Si838x. The datasheet seems to be saying it works like an opto coupler, where you obviously need the resistor in series with the input. However, the datasheet shows a bridge rectifier on the the input, so I'm not at all clear what's going on there. 

What about the outputs too? When I'm going the other way.from analogue domain to the micro, can I connect an analoguw signal directly to the input and then the output directly to the micro or do I need anything else on input or output.

I've Googled around for example real-world circuits and found the square root of nowt! :D

Many thanks,

Rob

 

 

Hi,

I designed AC and DC Load Switch with Si8752. AC switch is working well as expected. But high side DC load swtich is conducting even no input voltage. I tried it with FDMS1D4N03S mosfet. C4,R3 and D1 (TVS) are not populated on board during test. I tried miller capacitors seperately both of Source and Drain of the fet. I measured the gate voltage 0V in no control input and 10V in the control input on. But mosfet is conducting each situation ( control input on or off). How can I fix this issue?

Best regards,

 

 

I have a TTL circuit with 4 outputs which will handle 4 IGBTs,

I want to use Si826 AAC C IP dirvers between them, but datasheet says that I have to reach 5.6 V (maybe 6) when TTL outputs 4.8 or 5 V.    Did Silicon Labs did a product specifically incompatible with TTL so I have to do the interface of the interface?  Or there is a hint, a trick that makes it easy to interface TTL to this drivers?   Or the input can be TTL while feeding has to be higher than 5.6 V?

It somebody has done it, can you share it please?

Luis J

Is there a pspice model (proteus) for Si826 AAC C IP?

Hi,

I have a gate driver component, with a different suffix but I dont find anywhere what is the actual difference, and what does the suffix mean.

My components are the following:

SI8423AD-B-IS

SI8423AD-D-IS

Hi

We are planning on replacing digital isolators on a product range and need some guidance as to the suitability of the Si replacements. We have identified a couple of automotive approved parts as follows and would like confirmation that they are suitable for the stated isolation:

SELV to HV 400V Reinforced Isolation - Si8622ED-AS

SELV to HV 800V Reinforced Isolation - Si8622ET-AS

Please could you confirm that the parts selected are appropiate for the isolation requirements.

Also are both parts available with default output state low as there does not appear to be an option for this in table 1.2 of the datasheet?

Kind regards

Miz

Hi,

I am using Si8431 isolator for my RS485 circuits. Sometimes Si8431 isolators are broken after a while. I mean it is gone! Maybe because of ESD or over current or something else. I m not sure why this happen. The datasheet of Si8431 is writing "Not recommended for new designs". Why is not it recommended? Does it have problem related my situation. 

Thanks!

Mehmet

   Hi!!!

Can I use VDDA, VOA, GNDA for low side mosfet and VDDB, VOB, GNDB for hi side mosfet? Bootstrap diode will be connected to VDDB. Power suply +50V and -50V.

If yes, this is also true for Si 827x series?

Thanks!!!!

So, let me explain reasons.
I build full bridge class D power amp.
And will be good, if each half bridge will be mirrored to another half bridge on print board.  It is possible if one Si8427 in normal connection to output mosfet, and another with mirrored.

Hi, I am interfacing a TI balance charger that will report status by SMBUS.  It is running some high current motors in another section of the device and the charger is the central return for power/ground for all systems.  The SMBUS is unpowered and I have SDA, SCL, and GND from the charger board going to my microcontroller.  I am concerned about EMI reaching my microcontroller if I connected to the SMBUS directly. I am a little confused on the benefits of a fully isolated power supply, vs the practical EMI noise possible.

I was thinking of dropping the microcontroller system 3v3 to the VDD for the SMBUS side through a diode, maybe adding a bulk cap.  This would then prevent any spikes returning into the microcontroller system and maybe help prevent significant surges from the charger.  I know there are a lot of dumb isolation designs out there, but this one will sorta work I think.  Am I taking crazy pills?

any app engineer can tell us what is the nature of the output devices in the Si827x drivers? Specifically, judging from their symbols, one would conclude that there is no possibility of reverse conduction in these devises- neither through a body diode nor through a parasitic path. One important consequence of this will be that we can have a negative voltage at node B of the output without problem. True?

rg

1. What is the  maxim duty cycle of SI88621ED-IS (internal limit)? 

2.How to work for PWM control from empty load to full load? The frequency is constant ?

3.The min PWM width is 250ns ? or other figure ?

Thanks!

What is the ESD class of Si86xx series parts?

Where would I find documentary evidence for this?

Does anyone know what might cause the simultaneous failure of five SI8660BC-B-IS1 isolators? They are installed on a pump control board that uses stepper motors. Some are used for digital input to a micro, some for control of MOSFETS that switch relays, and some for driving the motor driver signals to the separate motor driver boards. All five died at once for an unknown reason and all their inputs are now low impedance to ground, i.e. about 2.5 ohms to ground measured with a multimeter.

Hello every one

I'm designing a half bridge converter with input of 450V and 4KW power ( 250KHZ<Fsw<350KHZ) using sic mosfets like this or similar.

I'm thinking about using si8274 due to its high CMTI, Fast switching timings, suitable gate driver current and deat time control btw high and low side mosfets.

regarding using SIC MOSFET specifically, it is mandatory to pull down mosfet gate voltage to negative (-3 to -5) due to low Vth of sic mosfet.

Also fast switching will produce higher ringing that further mandates pulling the gate voltage to negative, to avoid false triggering of the gate.

my questions are,

1 - how to supply si8274 negative voltage for both high and low sides of the driver ?

2- how to add short circuit protection function, Like soft DESAT (usually used for IGBTs) to SIC mosfets?

appreciating any help

Thank you

Ismail

Hello all,
Currently, we are using below isolators in the same single PCB.
        SI8661BB-B-IS1 = 2 nos
        SI8662BB-B-IS1 = 1 no
We have given, supply voltage 5V and 3.3V DC from the DC/DC convertor.
As given in the datasheet, Do we need to use supply bypass capacitors for 3 IC's Seperately?
Since, 5V and 3.3V DC supplies are shared together, can we use bypass capacitors only for one IC?
Kindly give your valuable feedback.
Thank you.

Regards,
S.Saravanakumar

Hello. Si890x has 0.5 PGA setting. Does it mean it's possible to measure input voltage greater than Vref? If not how can this gain to be used?