Buck converter with MOS gate driver Uc3843 + IR2110 - Page 1
Forum section: electronics / projects

author: tural_h
author_rank: Newbie
timestamp: December 18, 2024, 03:36:29 am
content: Hello everyone,I want to design a buck converter using the UC3843 in voltage PWM mode along with the IR2110 high-side driver for an N-channel MOSFET. The main goal is to step down from 60V to 12V with an output current of 3-5A to drive a DC motor. In simulation LTspice, the circuit works. I plan to power the ICs using a separate DC-DC buck converter (XL7005), which operates from 80V to 12V with a maximum output current of 700mA.I have two questions:1. Has anyone built a buck converter using the IR2110 by utilizing only its high-side channel?2. Will the IR2110 work with the UC3843, where the PWM source is an asynchronous commutator?If you have any alternative ideas or suggestions, I'd appreciate them. At the moment, the PWM controllers I have on hand are the UC3843, TL494, and SG3525. Thanks in advance for any help.In this simulation i used 30v instead of 60 but it works in LTspice

author: Konkedout
author_rank: Frequent Contributor
timestamp: December 18, 2024, 04:42:38 am
content: I have been designing power supplies for many years. I do not know why your scheme would not work. But that does not mean that it will work.I do notthinkthe high side low side gate driver chip needs to have the low side used in order to use the high side.Do you need to have negative ground? If not, it might be easier if you switch the low side instead of the low side. That would make for easier drive (might not need the gate driver) but you would need an op amp or other means to measure the differential voltage across the load and provide feedback to the UC3843.

author: johansen
author_rank: Super Contributor
timestamp: December 18, 2024, 05:59:01 am
content: Just make sure there are no conditions by which you need the low side driver to ensure that the boot strap diode can charge up the high side driver..

author: mtwieg
author_rank: Frequent Contributor
timestamp: December 18, 2024, 06:57:43 am
content: There are some conditions under which using a bootstrap high-side driver without a synchronous switch can fail. Basically if the bootstrap supply voltage (VBS) ever falls below the IR2110 UVLO threshold (roughly 8V), then the IR2110 will cease operating until Vout falls low enough such that VSB can recover. This can occur if the PWM controller and IR2110 power up after Vout is already high (often the case if the load is a battery or other kind of DC power source). Also in very light load conditions, the freewheeling diode may fail to conduct even if the high side driver is still producing pulses, in which case VBS may still fail.Basically as long as the load on the output is enough to get the freewheeling diode conducting, you should be ok.

author: tural_h
author_rank: Newbie
timestamp: December 18, 2024, 08:47:55 am
content: thank you very much for the explanation, I want to assemble this circuit and see how this circuit will work, the load is a 12V DC motor, maximum current 3-4A

author: Konkedout
author_rank: Frequent Contributor
timestamp: December 19, 2024, 03:41:27 am
content: Quote from: mtwieg on December 18, 2024, 06:57:43 amYes that is correct. I forgot about that issue in my earlier post. I have used controller chips which use a bootstrap capacitor and only a freewheel diode (no synch rectifier). They can run into trouble when there is not enough load current.