I am using the SI3402 chip to use POE.
But it does not work properly.
The circuit I have constructed is as follows.
POE: SI3402 (non-isolated)
Ethernet Transceiver: H2019NL
When POE cable is plugged in, it charges for the first time but it becomes impossible to charge soon. I think that the POE side circuit is a problem because I operate normally when only 5V is applied to the charge IC.
Since it is confirmed that 5V is output from the output terminal, it is not a voltage problem.
I attach the schematic that I composed with PDF.
Please make sure that there is something strange in my circuit.
I'm looking for the IMRR of the Si8920.
In the datasheet I find a CMRR vs frequency (Fig.7) but I think it's the CMRR referred to the input common mode voltage.
But I'm not sure if that's true.
Can anybody help me with this problem?
I am interested in using this opto-coupler in my design in which I need the opto-coupler NOT to turn on below 2mA. Based on the Si87xx datasheet on page 4, the Si87xxA has input curent min at 3mA and Max at 15mA. It also has input current threshold IF(TH) at 1.8mA max. Does this mean the LED of the opto will turn on at 1.8mA or at lower current than that? Or does it turn on even at lower than 1.8mA?
Appreciate your help on this.
The datasheet for these devices https://www.silabs.com/documents/public/data-sheets/Si827x.pdf gives a high level peak output current of 1.8A (2.7ohm RDSon) and a low level peak output curren tof 4A (1.0ohm). These values are VDDA/B = 15V. I plan on running this driver around 5V for a GaN FET application. How will the drive high and low RDson change accordingly?
Are there accurate spice models of these devices?
We are using Si8230 for driving GanFET's in a Half bridge LLC topology. we are using a single 15 V power supply along with boot strap circuit
to power up Vdda and Vddb. Very often we see that the driver is getting failed. Pls let us know what are all the possible failure modes of this driver.
I recently bought your amazing dual gate driver Si8275ABD. I've to use it in my bachelor degree's final project. I'm unable to find any model of the device for simulation purposes. It is requested that any available model kindly be provided to us at your earliest ease for this educational learning opportunity.
Hi Silcon labs team,
I am currently working on a high end class D powerstage in which I'm considering a gatedriver in the SI824x range. The advertised feature of these chips above the regular SI823x series is the precision deadtime, but there is no tolerance specified in the datasheet of SI824x.
From the datasheet of SI823x, the programmed dead time for a RDT of 6kOhms is specified to be 70ns nominal, with a min of 55ns and a max of 75ns, for a tolerance of +/-21%. What would be the improvement in dead time tolerance be in this range if we went for the SI824x series?
Also, we are considering using variable deadtime. is this supported by these drivers and if so, can we control the deadtime cycle by cycle?
Thanks in advance.
i have 3 h-bridges here with the same issue. When i feed a 50% duty pwm to the driver and there is a current of approx 10A flowing through the FETs i have sporadic errors in the low side gate drive.
The high side goes as expected to 0V (VGS) and then the low side gate starts to rise, at approx 90% of the rise the VGS drops to 0 with a sharp edge no discharge of the gate capacitance in there. Then the turn on of the low side starts again und reaches its turn on level.
At first i thought i would be an disturbance on the EN Pin due to the fact that in the fail event both gates are low but fixig EN to 3V3 volts changed anything.
Does anyone have a hint where to look at? PWM is 24kHz at 30V input. The Gates are supplied by -5/10V. The input PWM is fine and 3V3s is also fine.
Thanks in advance.
After over 10 designs with the SI3402B, I need to make a POE circuit that is only rated to 3W instead of the 15W normal solution as your reference design.
So Im looking to reduce some of the components like the D3 PDS1040 and the transformer FA2924 from your reference schematic
For the Diode this is straight forward but the for transformer I not sure how flexible the circuit is.
I been looking at the Coilcraft POE30P-33L_ seriel but this also have a bias coil thas is not needed and also the turn ration is different compared to the original version.
Since we are using rough 50K pr year I can perhaps get a costom version that will fit my need.
Any idea of some lower rated transformer you can suggest ?
We are using SI8274 driver for an Half bridge LLC Application. we are using a 5 V power supply for Vdd1. And two separate isolated 15V power supply for Vdda and Vddb.
The PWM pulse was given from a micro-controller. At the first instance, we got the both the outputs with dead band. Very shortly one output was become zero. Then we found that the power supply for Vddb was over heated, which happened because the Vddb and gndb was showing short..
Then we replaced the driver with a new one. This time the same happened with Vdda and once again the driver failed. I have also attached the schematic.
Kindly help us to identify/resolve the issue.
I am using IC SI8631AB-B-IS1 for isolation , this pin has EN1 and EN2 , Can this pin be left floating for proper operation on this isolator, since thies both EN1 and En2 internally pulled up.