IR2110 and two low side FETs - Page 1
Forum section: electronics / beginners

author: 09d08
author_rank: Contributor
timestamp: August 22, 2018, 11:21:22 am
content: Hi,I need to drive two low-side N channel FETs with an ATmega328 for a project I'm working on. I thought that using a driver IC would be the best option but I only have but I only have some IR2110s available. I've never seen this IC being used for anything other than driving half bridges so is it possible to drive two low side FETs with it?

author: langwadt
author_rank: Super Contributor
timestamp: August 22, 2018, 11:24:39 am
content: yes

author: b_force
author_rank: Super Contributor
timestamp: August 22, 2018, 11:43:01 am
content: With only two low-side MOSFETs you can just simply use two buffers, since you don't need the bootstrap anymore.

author: langwadt
author_rank: Super Contributor
timestamp: August 22, 2018, 12:01:38 pm
content: Quote from: b_force on August 22, 2018, 11:43:01 amand an IR2110 has two nice 2A buffers

author: b_force
author_rank: Super Contributor
timestamp: August 22, 2018, 12:10:26 pm
content: Quote from: langwadt on August 22, 2018, 12:01:38 pmI know, I am very familiar with these IC'sBut the main reason to go for an IR2110 is because of the bootstrap (half-bridge)If you don;t need that, you can just simply use a totem-pole buffer

author: 09d08
author_rank: Contributor
timestamp: August 22, 2018, 12:16:55 pm
content: Normally I would use a TC4427 for this application but the last one I got decided to release the magic smoke recently. Since I don't have any buffer ICs so I tried to create one with two BJTs but the result wasn't as good as the one I got with the TC4427. So should I try to improve the BJT driver or use the IR2110 without the bootstrapping capacitor and diode? I'm not really sure what changes I would have to make to the diagram given in the datasheet to make it suitable for my use case.

author: b_force
author_rank: Super Contributor
timestamp: August 22, 2018, 12:23:22 pm
content: This is an excellent document for buffers and such;http://www.ti.com/lit/ml/slua618/slua618.pdfLook for the totem-pole buffer.Why your TC4427 burnt up in smoke I don't know.That thing is capable of delivering a lot of driving current, so obviously something is wrong with your circuit.

author: 09d08
author_rank: Contributor
timestamp: August 22, 2018, 01:04:51 pm
content: Thanks for the informative link. I think I'll try building a totem-pole driver with a PNP on the high side and invert my PWM drive signal.

author: Alex Nikitin
author_rank: Super Contributor
timestamp: August 22, 2018, 02:10:05 pm
content: Quote from: 09d08 on August 22, 2018, 12:16:55 pm"The BJT Driver" you've drawn will also go up in smoke... .CheersAlex

author: 09d08
author_rank: Contributor
timestamp: August 22, 2018, 02:23:08 pm
content: Quote from: Alex Nikitin on August 22, 2018, 02:10:05 pmCare to explain what exactly is wrong with it?

author: Alex Nikitin
author_rank: Super Contributor
timestamp: August 22, 2018, 02:25:34 pm
content: Quote from: 09d08 on August 22, 2018, 02:23:08 pmJust calculate the power dissipation on the NPN device when it is conducting.CheersAlex

author: David Hess
author_rank: Super Contributor
timestamp: August 22, 2018, 05:17:37 pm
content: Quote from: 09d08 on August 22, 2018, 02:23:08 pmThe current drawn out of the base of the PNP transistor is unlimited. This could be corrected by moving the top of the NPN collector resistor to the base of the PNP. A parallel resistance between the base and emitter of the PNP should also be added.

author: Ian.M
author_rank: Super Contributor
timestamp: August 22, 2018, 05:39:41 pm
content: If one wanted to use an IR2110 as a dual low side driver, one would strap Vs to COM and Vb to Vcc. Operation with Vs tied to COM is explicitly permitted as that's what datasheet Figure 3. Switching Time Test Circuit simplifies to with Vs at the minimum indicated level of 0V relative to COM.

author: Seekonk
author_rank: Super Contributor
timestamp: August 22, 2018, 09:14:17 pm
content: Many inverter designs do the same thing and use the 2153 oscillator half bridge as two low side drivers to make simple push pull inverters. A nice one chip solution.