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Comments?
Long story short, the p-channel mosfet won't conduct, and therefore won't connect the down-stream devices to power, if power is reversed.
Using LDO's was suggested since my motorcycle has a permanent magnet 3-phase generator and the regulator shunts excess current to ground via SCR's. If I were being 'jump started', the regulator would already by dumping current the bike doesn't need to ground on its own.kb1gtt wrote:ISO spec for load dumps and such can be found in a link from this thread http://rusefi.com/forum/viewtopic.php?f=4&t=199&start=14
We need to know the load and load conditions to make better comments. However I would wonder why you are looking to remove the diode to gain some efficiency with the reverse polarity protection, but are ignoring the linears efficiency. For easy math, I'll assume 1A. So the diode with about .7V drop would dissipate .7W. However the linear dropping from 13V to 3V at 1A will dissipate 10 watts, while delivering 3 watts of power. So about 30% efficient, which is blah.
Also you can get load dumping on the regulated side, so I'd suggest a small diode across the linear to prevent the output voltage from exceeding the input voltage, and transient TVS diodes to prevent front end spikes. The next issue I see is that it doesn't block ripple very well, so expect AC ripple from the 12V to be seen on the regulated side.
The TPS54360 is a 60 V, 3.5 A, step down regulator with an integrated high side MOSFET. The device survives
load dump pulses up to 65V per ISO 7637.
Would like to help but I use Eagle, not to mention I'm stumbling upon these parts for my project. That's why I titled the topic "possible suggestion", sharing what I'm finding, for you to consider for your project.russian wrote:Is anyone interested in drawing the actual board, ideally in KiCad? @?
Besides the fact I have no idea exactly what you're talking about or referencing since you choose to post things without quotations or other things... 40 mS?kb1gtt wrote:It's my understanding the 5V for 40mS spec, is mostly caused by battery chemistry. Basically when you start cranking, the rapid change in load takes a fraction of a second to get the chemical reaction happening. It can happen with a new/good battery, and will happen more often with a deep cycle battery in cold weather. Commonly batteries are made with that lead foil, which acts similar to a capacitor. This also can cause the battery be slightly sluggish as the foil being pack close together changes how the acid from circulates around the electrode.
I think I forgot to mention these, set for 6-18v in, 2.0A out and 60v input transient tolerable. They require 6 volt to start, but low-dropout is around 4.3v.kb1gtt wrote:I've been meaning to reply, but time and resources = blah. Here's a quick one.
I see a 7V min, I think that needs to be closer to 5V. On the 5634 IO board I used the MAX5093B which does both buck and boost. It can go down to about 4V and up around 70V. It also has a ripple free output and will buck and boost, so you can get 5V with a 4V input. The down sides is that it can only do about .25 amps. Also there was a minor issue with the one I did on the IO board, one of the caps really needed to be a lower ESR. The cap would get a bit warm.
Here's a note about the voltage dip during cold cranking. http://www.maximintegrated.com/app-notes/index.mvp/id/4240
So I'd like to suggest we plan for the battery to dip to 5V for 40mS.