How is the nMOS here acting as a capacitor

In the textbook “CMOS Digital Integrated Circuits” by Sung-Mo Kang et al on the topic of Voltage bootstrapping, they use a dummy MOS device with the Drain and the Source terminals connected to realise the bootstrapping capacitor Cboot (whose role is to increase the value of Vx). How does such an nMOS act as a … Read more

Simulating IR2104

I have this simulation set up in Every Circuit. It can be viewed here: http://everycircuit.com/circuit/5875415639916544 For right now I have turned off M3 by jumpering M3’s gate to the ground nearby. Simulating with an 18V solar panel and a 12V battery I can see in Every Circuit that when M1 and M2 are on there … Read more

Choosing bootstrap capacitor for MOSFET driver

I have IRS2011 high/low side MOSFET driver, for driving IFRZ44N MOSFETs configured in H-bridge. How would I calculate the bootstrap capacitor required by the IC for driving high-side? I am aware of the equation in this pdf, but since these wont drive the H-bridge continuously I dont know what to use for the frequency. I … Read more

I am designing a boost converter for wind turbin, with load 12Vdc, 2A. Before I install my boost converter on my windturbin, I putt a test to make sure it work properly. So I use this circuit to simulate the battery represent power supply and I use tip142 as the gate driver. with no load … Read more

Buck not acting as designed

I have designed a synchronous buck converter to step down a 17.4V voltage source to 12V at the output. I have attached the schematic as shown. Problem: The Buck is not operating as expected at all. Here are the measurements I was able to get from testing it: PWM frequency: 62.5kHz Vg of M1 = … Read more

What design considerations determine what kind of power supply I should use for a high-side FET?

I’m presently considering building a half-bridge converter, which means I have a transistor that’s not tied to circuit common. To drive it, I’ll need some voltage supply referenced to its source. This is a common problem with many switching topologies. I’m aware of two general ways to power such a driver: a magnetically isolated DC/DC … Read more

Buck converter as a LED driver with NO LOAD

I am proceeding with a design of a LED driver using an LM3405. I don’t read anything related to what happens when the load is not present, on the datasheet. As you may have already read, this is the configuration adopted. But with open load, the output does not simply goes to Vin? When the … Read more

H-bridge using solid state relay instead bootstrap IC

experts! Good afternoon. I am working on a project using a H-bridge. It must work at 100V and, then, i first designed a bootstrap circuit with 2 IR7304S (attached picture). Then i was wondering if two solid state relay could perform the same thing, replacing the bootstrap circuit and removing the MOSFETs. The objective is … Read more

Bootstrapping in discontinuous mode

I am designing a buck converter that would charge a battery and planning to use an N type MOSFET on high side and FAN7085_GF085 driver to go with it. Datasheet: (Can’t post more than 2 links, sorry). Application note: https://www.fairchildsemi.com/application-notes/AN/AN-9052.pdf If the converter happens to go to discontinuous mode however, the diode stops conducting -> … Read more

Mosfet bootstrap voltages

I have a question regarding using an n-channel mosfet in the high side with a charge pump bootstrap. Lets assume the following: Vgs max is 15v Vgs(th) is 2v (logic level) voltage pressent at source pin is 10v charge pump is charged to 20 volts all grounds are common Now, the voltage at the gate … Read more