Difference between the VNLD5300 and VNLD5090 - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: August 13, 2020, 06:30:45 am
content: I have been looking for a low-side mosfet driver IC and found theseVNLD5300which is a 300mOhm 2A driver and theVNLD5090which is a 90mOhm 13A driver. I would like to do one last sanity check, the 5090 seems to be a much more superior IC am i right? But what strikes me is as weird for the same package can the 5090 really handle that current? they are priced very close too so i assumed that ST electronics made these 2 version intentionally with different purposes.My application is controll and inductive coil at 1.5A both IC fit the application, would going for the 13A 5090 good for me ? What could the reason be that there is a skew with an inferior rating, because i dont think its cost, since they are priced that close.

author: magic
author_rank: Super Contributor
timestamp: August 13, 2020, 06:41:45 am
content: It can only handle 13A peak, not continuously - do the math on power dissipation. It will discharge your gate much faster than the other chip, though.I imagine one reason for preferring a slower driver, besides price, may be less switching EMI.

author: drakejest
author_rank: Regular Contributor
timestamp: August 13, 2020, 06:51:31 am
content: Quote from: magic on August 13, 2020, 06:41:45 amI assumed that the higher value amperage was the peak (25 A for the VNLD5090). Having a second look at it, i could not find the true maximum current for the device and is written as "internally limited" under the electrical characteristicsQuote from: magic on August 13, 2020, 06:41:45 amcan you guide me sir on how to do this ? what parameters should i use and how do i use them so that i can know if im safe on my application on open air with no heatsinks?

author: magic
author_rank: Super Contributor
timestamp: August 13, 2020, 07:10:49 am
content: For continuous current through the output stage MOSFET it's simply I²·RDS(on), like with any other MOSFET.When driving an external FET, it depends on gate charge and switching frequency.

author: drakejest
author_rank: Regular Contributor
timestamp: August 13, 2020, 07:47:35 am
content: Quote from: magic on August 13, 2020, 07:10:49 amI do not quite understand how to use the formula, Isnt that a formula for power P=I²·R. I am missing the P, R is 0.09 ohms, I² is my missing variable. So i cant solve the continue currentQuote from: magic on August 13, 2020, 07:10:49 amcan we assume then 100% uptime?

author: thm_w
author_rank: Super Contributor
timestamp: August 13, 2020, 10:31:02 pm
content: QuoteUse this number in the datasheet to get a rough idea of maximum power dissipation. So 150C max - 25C ambient = 125C = about 1W.Real result will depend on how its mounted to your board, if its heatsinked, etc. and whatever headroom you want to include.

author: David Hess
author_rank: Super Contributor
timestamp: August 14, 2020, 04:09:23 am
content: The higher current chip is more expensive because it has more area but the primary difference is the current limits. You would not want to rely on the 18 amp current limit in an application that only requires 2 amps.