# Questions tagged [rdson]

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### Estimating GaN HEMT junction temperature

I think it's quite a simple question, but the solution is not so obvious for me. I know the equation Tj=Ptot×Rth+Ta, the thermal resistance Rthj-a and RDSon temperature dependance come from the ...
• 11
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### Is this setup for measuring MOSFET RDS_On correct?

I ordered some MOSFETS from AliExpress and I think I've been duped. The diagram below shows my setup: If I'm not mistake, this means that the R_DS(On) of this N-channel MOSFET is 0.042/0.62 = 67 ...
1 vote
768 views

### LTspice - What is the best way for having Rds(on) curve of a MOSFET?

I am trying to get the Rds(on) of a MOSFET. I have tried different methods and I do not know what is the best method. There might be a method that is better than the ones I used. In practice, it seems ...
• 2,478
59 views

### P-MOSFET Rdson values with Vgs near maximum

My understanding is that a MOSFET's Rdson generally decreases with higher absolute Vgs values within its specified range, and I typically consult datasheet curves showing Rdson vs Id and Vgs. I'm ...
• 55
192 views

### DC-DC boost converter theory / principle / testing

I am trying to setup a DC-DC boost converter circuit that can convert 50-60 V DC to 86.4 V at the most current I can achieve a reasonable efficiency of say 90%. Mostly for the learning curve but my ...
• 339
1 vote
71 views

### Mosfet Rdson inconsistency in datasheet? Or conceptual error?

I was checking the datasheet for the Allpower AP2012S and while checking the graphs to determine the Rdson in my point of operation I found what I think might be an inconsistency, however, I wanted to ...
82 views

### Help solve rds for pchannel FET from this datasheet

I would like to use a pchannel FET as a voltage controlled resistor in a circuit where my voltages are between 0 and 1.1 Volts. I'm hoping to use the J175 but truthfully I am having a difficult time ...
• 165
1k views

### On-state resistance limit in the MOSFET safe operating area figure

I'm trying to understand the upper-left corner of a typical MOSFET safe operating area (SOA) figure. Specifically why the region marked in red on the figure below, above the "Limit Rds(on)" ...
• 341
1k views

### How to determine the Rds(on) from a MOSFET datasheet

I want to know the RDS(on) of this MOSFET when VGS = 3.5 V, and ID = 5 A . As you can see, the graph stops at 2.5 A. data sheet link: https://pdf1.alldatasheet.com/datasheet-pdf/view/555356/...
• 23
338 views

### Precharge MOSFET safe operating area with inline resistor

I'm looking to use a MOSFET to turn on a resistive path, precharging a capacitive load. I'm considering the Nexperia BUK9608-55B, but I'm having trouble determining what my operating point is on the ...
• 127
1 vote
1k views

### RDS measurement on P-Channel MOSFET

I want to measure the Rds-ON of a P-Channel MOSFET and I have setup the test circuit as follows: I keep the source at constant +10V and vary the step the gate voltage up in the increments of 1V. Then ...
166 views

### How can I calculate the worst-case Tj of a MOSFET in discontinuous operation at another Tamb?

I am faced with the task to calculate the maximum junction temperature of a MOSFET in a half-bridge, having conduction losses, switching losses and diode losses. The real difficulty comes from the ...
• 720
1 vote
127 views

### MOSFET Gate Charge dependance on temperature at HOT, to determine charge needed to design driver?

i am designing this push and pull driver for external NMOS in my buck topology circuit. i am well aware the gate charge ( based on Cgd) i need to turn FET ON and OFF at room temperature based on ...
357 views

### JFET RDS(on) Matching

Quick question here - I have a circuit that originally used a 2SK30ATM-GR JFET, with an RDS(on) maximum of 800 ohms. Most of the cheap JFETs I can find have a significantly smaller RDS value, ...
• 135
375 views

### MOSFET Vds and SOA graph

I have a question regarding the SOA graph and a low Vds voltage (below 100mV), I will get to the questions below but needed to layout some information first. I am looking at a International Rectifier ...
• 101
453 views

### JFET resistance and transconductance

The book says the rds of the 2N8461 JFET can be varied from 100 ohm to 10Meg. I went on and tried to verify this using the equation and plug values in it from the datasheet using the minimum values ...
• 95
199 views

### Am I calculating my shunt FET power dissipation correctly?

simulate this circuit – Schematic created using CircuitLab I'm designing an LED driver circuit that requires very fast PWM switching at a high resolution (10bit at 30khz requiring a minimum ...
• 362
671 views

### Calculate MOSFET Forward Voltage Drop

I'd like to better understand how to calculate the voltage drop between the Drain and the Source of a FET. As an example, say we have a MDD1902 N-channel FET. How would I determine the maximum ...
• 99
472 views

### MOSFET with very low Rds_on for very small current

I'm building a uCurrent Gold clone (https://www.digikey.ch/reference-designs/de/sensor-solutions/current-sensing/2637) - with a digital interface (measuring the voltage directly with a microcontroller)...
• 11
3k views

### Paralleling mosfets to reduce Rds On?

This if a fairly simple question. I have some APT43M60L MOSFETs with a fairly high on resistance. They get quite hot and waste a lot of power in my induction heater. They work great but get really hot ...
153 views

### Dual N-channel mosfet Rdson value

I'm going though datasheets of some dual N-channel MOSFETs for li-ion battery protection, like 8205A or ECH8695R, for some thermal and power dissipation calculations. There are Rds(on) values, like ...
• 5,508
146 views

### Help needed in understanding MOSFET datasheet

I am trying to find a logic level MOSFET for 3.3V operation. In my case, I am trying to compare AOD510 & AO4402. AOD510: $\mathrm{R_{DS(on)}}$ @ 4.5 $\mathrm{V_{GS}}$ = 0.004 ohm but has no ...
• 2,162
1 vote