I am trying to control a LS5FN-3035-CC DC brushed motor from Transmotec (12V, no load current 0.5A, stall current 13A), with the need of a torque that it can reach for a 5A for less than 5 seconds once every 20sec. I thought that the need of power for such a small period of time will allow me to use “medium power drivers”.
I want to control two motors with the same target.
I tried the Pololu 2999 ( TB67H420FTG) with a current limit threshold of 4.5A and 2 Pololu 4039 ( DRV8256P) with a current limit of 6.5A.
However, has it is written in the documentation of this evaluation boards, the thermal security is happening for values far below the current limitations (I could not get more than 2A) and I was increasing the pwm slowly.
I tried to add a heatsink that I put on top of the VQFN package (or for the TB driver on the other side of PCB as it has a thermal drilled pad), but the improvement was not spectular (could not get more than 3A).
I know that I could use one of the “High power drivers” that you do, but they look overkilled for my need.
I am looking for the cheapest driver that can fit my need. I also wonder why there is such a gap in continious power limitations of drivers.
Unfortunately, I do not think the motor drivers you tried (the TB67H420FTG or the DRV8256P) are appropriate for a motor with the specifications you provided. Our general recommendation is to use a driver that can handle continuous currents at least as high as the motor’s stall current, so I would recommend one of our G2 High-Power Motor Drivers instead.
I am not sure what you mean when you ask about the “gap in continuous power limitations of drivers.” Can you be more specific?
Thank you for your answer.
My question was about the maximum continious current that dc brushed drivers can support.
The Low power driver category has values between 0.9 and 3A.
The Medium power category has values between 2 and 9A. (Except VNH5019).
The High power has values between 12 and 25A. (Including VNH5019).
From your catalog there is not a big gap on maximum, but there is a price difference between medium and high.
I checked the Toshiba and TI catalog of drivers for brushed dc motors and it seems that you already uses their drivers with the maximum continuous output current. I am wondering why they do not sell drivers with higher values (Is it that market is not much interested in it ?). The fact that they do not provide your “High power” category is the reason of my question about gaps
You do not provide datasheet of driver nor schematic for the G2 boards, why is that ?
Regarding your questions about why there aren’t more higher-power single-package motor drivers, I think the main reason is that higher power requires bigger chips, and big chips are not cost effective. Even something like the VNH5019 has separate silicon chips in the one plastic package that we think of as the chip or IC.
For pricing, everything is distorted now because of the chip shortages, so don’t expect it to make sense in terms of price per performance. There are many cases where a worse-performing product is more expensive just because we cannot get the parts for it. We expect the gaps to be smaller when part availability returns to normal.
There are many business considerations that go into how much internal detail we disclose for various products.
I want to thank Pololu employees for your fast and complete answers to my questions.
Have a good day,