Electronics > Projects, Designs, and Technical Stuff
Boost-buck for pump
Scrts:
For that current, you will need buck-boost controller with external FETs. Have a look here: http://www.ti.com/power-management/non-isolated-dc-dc-switching-regulators/buck-boost-inverting/buck-boost-inverting-controllers-external-switch/products.html
I'd say your search might be referenced with automotive grade truck power supply, since trucks use 24V systems.
angrybird:
If he goes buck only, he could use an integrated part. Dropout operation will need to be analyzed, though. Dropout specifications for SMPS are "murky" at times :D
(i.e. 99% duty cycle may not actually mean 99% duty cycle :-DD)
andrew_c:
Yes, I believe a buck-only option would now be most suitable. Our business is rather new to the electronics market, this would only be our second commercial venture.
We shall be looking to comply with BS EN 60601-1-2:2015; which we've successfully navigated in the past.
The pump manufacturer has highlighted that the specific series of pumps we intend to use (not in my hand yet) are rated at just 35W, so just 1.5A if this helps with any further suggestions.
To meet the demands of the pump before the batteries internal cut-off is activated, we would need to see a duty cycle >98%. I'm certainly happy to handle a few parts to find one that works.
fcb:
Anything can be made to comply with EMI - at a cost.
SEPIC is good if you need to meet your original specification and just want to run a simple motor. You will need to consider stall/fault conditions. TI make some great free selection and design tools for this:
If need to control pump speed (sounds like you don't), then I would use a boost configation (if you need>=24V) with a PWM MOSFET.
Probably wait till you get the pump in-stock and then carefully characterize it's performance in your real world application.
angrybird:
--- Quote from: andrew_c on March 06, 2020, 10:44:29 am ---Yes, I believe a buck-only option would now be most suitable. Our business is rather new to the electronics market, this would only be our second commercial venture.
We shall be looking to comply with BS EN 60601-1-2:2015; which we've successfully navigated in the past.
The pump manufacturer has highlighted that the specific series of pumps we intend to use (not in my hand yet) are rated at just 35W, so just 1.5A if this helps with any further suggestions.
To meet the demands of the pump before the batteries internal cut-off is activated, we would need to see a duty cycle >98%. I'm certainly happy to handle a few parts to find one that works.
--- End quote ---
Just be aware that maximum duty cycle is a specification that suffers "marketing" effects at many IC manufacturers. 98% may not truly be 98%, the first thing you need to do is dig deeper, look at min off time (if they even specify it), get an evaulation board and look at it on the bench under your operating conditions. Depending on what type of high side drive they have, look at the BST capacitor and make sure you aren't running out of charge at high duty cycle. Companies like TI play a lot of games with the specs on their more competitive parts :D
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