DRV103 vs mosfet to drive valve - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: December 08, 2024, 02:49:36 am
content: Hi,I am thinking of driving the valve in the attached datasheet from a fixed 24V rail. Are there any advantages in controlling it with the DRV103 (datasheet also attached) instead of a common mosfet?The fastest switching is only a couple of times per second.I am asking because according to some posts online the maximum and holding currents for DC operation are the same which does not make much sense. Is that actually correct?Thank you

author: Psi
author_rank: Super Contributor
timestamp: December 08, 2024, 03:06:01 am
content: The inrush current kind of makes sense for AC, since it might connect when waveform is at peak. So for 24V that would be a possible 34V with high inrush current.Not sure about holding power,You'd think 24VDC vs 24VAC RMS would be the same and either both need holding mode or neither need it.So i dunno why it's only given for AC. Probably just for reference.As far as mosfet vs driver IC goes.The main advantage is short circuit/fault/temp protection. The driver will shut off and protect itself, whereas a mosfet will explode.Both options need a back EMF diode so you don't save anything there either way.The driver uses a nfet to switch to ground, so it's not like you gain high side switching.There are some driver ICs that can handle an inductive load themselves and don't need the diode, but not that one.Have you considered a SSR, might be easier if you don't need PWM.

author: coppercone2
author_rank: Super Contributor
timestamp: December 08, 2024, 08:13:41 pm
content: well if you do solenoid control, having intelligent control (i.e. power saving to reduce solenoid heat while its on) that comes with some driver IC is actually a big deal.There is the green part (market wank, a few watts less in a factory), and the "your expenisve ass valves and actuators don't burn up as much and we don't use some kludge MCU circuit to do it' part. Especially if its connected to coolant, gas, or something clean (stainless).I mean some solenoids can easily dissipate 20% or less power if driven smartly in alot of situations. That means something on the 'wear and tear' curve.I would say it really starts to shine if you can offer the 'intelligent' control.if you have not noticed, solenoids seem to be one of those things that get HOT.

author: wraper
author_rank: Unknown
timestamp: December 08, 2024, 08:28:03 pm
content: If you drive mosfet from MCU, you can easily implement all DRV103 functionality in firmware. IMHO it's yet another lazy engineer type of part that makes zero sense at its price. Heck, throwing in a dedicated MCU that controls just a single mosfet is an order of magnitude cheaper than that.

author: coppercone2
author_rank: Super Contributor
timestamp: December 08, 2024, 08:30:17 pm
content: solenoid valves can easily cost into the multi thousand dollar range. maybe its not a choice for a budget sprinkler system

author: wraper
author_rank: Unknown
timestamp: December 08, 2024, 08:35:20 pm
content: Quote from: coppercone2 on December 08, 2024, 08:30:17 pmMaybe, but this is just a super dumb IC with dubious drive capability. Its 0.5 ohm on-resistance in SO-8 package by itself should rise a doubt about how much it will be heating and thus how reliable it will be.

author: coppercone2
author_rank: Super Contributor
timestamp: December 08, 2024, 08:37:35 pm
content: and often the fluid or gas its controlling is plenty hot, its located in a bad area, and its expenisve despite being small. I bet its actually not that uncommon for super expensive parts, if you need... somewhat reliable control for slightly salty water or something like that. 5% calcium chloride @ 90C , or maybe fluorine gas, abrasive liquid, hot abrasive liquid, etc. Or hot gasses might be driving a tiny valve to 95% of its thermal capacity without the power being turned on at all. Chemical engineer shit is basically rigged to blow within design specifications.and things like it getting hit with a plume of errant steam when they open something or another (not designed for)Keeping power low is always a good idea

author: ricko_uk
author_rank: Super Contributor
timestamp: December 09, 2024, 07:58:26 am
content: Thank you all