Automotive power supply for Teensy

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log_335

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Seeking some opinions on the attached power supply schematic. suitability, functionality etc

input voltage will be around 13.7v with engine running

D1 1N4003 to provide protection against reverse connection

TVS diode is a P6KE15A. datasheet [wrong symbol on schematic]

OKI-78SR-5 dc/dc datasheet regulator to provide 5v to teensy 3.5 or 3.1 and some 5v sensors (mpx4250's or similar, outputs are connected to analog pins through voltage dividers)

the 5.6v zener is to protect against reg failure, will need to be man enough to pop the fuse :D

will be used in my data logger project. any advice welcome, i am a beginner

power.jpg
 
mdFZhAXw-llzAm2qRhaIXmg.jpg

This is what I use in my automotive project. It's an 8v-40v input and 5v 30a output dc-dc ~90% efficient psu, epoxy sealed and weatherproof. It also survives cranking, the lowest voltage I've tested for a drop out is 7.60 volts, however, once the voltage goes back up, it restores the 5v rail, and the voltage doesnt seem to fluctuate either on my DMM.
Enjoy

Also: Cut VIN-VUSB pad (Once you do that, Teensy only works with external power connected), or, option #2, get a data-only usb cable or make your own, by cutting it's red wire
 
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15 V might be a little too low for the TVS -- as the battery goes bad (but not failed), the voltage could approach 15 V -- together with the TVS tolerance, it could cause some current to flow and it might overheat (and not blow the fuse). Try 18-24 V version.

if you care about keeping operation during low battery (e.g when cranking the engine on a cold day), make the input cap larger -- to 1000 uF or more (but watch for the fuse blowing when you connect it initially -- may need a slow-blow fuse). The 78Sxx needs 0.1 uF caps also -- placed close to the chip. If your load current is only 10's of mA or so, it won't need (much of) a heatsink, but if you are driving heavier loads, it might (e.g. 50 mA ==> (14 -5 )*50mA = 450 mW
 
View attachment 9181

This is what I use in my automotive project. It's an 8v-40v input and 5v 30a output dc-dc ~90% efficient psu, epoxy sealed and weatherproof. It also survives cranking, the lowest voltage I've tested for a drop out is 7.60 volts, however, once the voltage goes back up, it restores the 5v rail, and the voltage doesnt seem to fluctuate either on my DMM.
Enjoy

Also: Cut VIN-VUSB pad (Once you do that, Teensy only works with external power connected), or, option #2, get a data-only usb cable or make your own, by cutting it's red wire

got a link??
 
that one is 3A. get the 30Amp version, i buy em from ebay as well search for 150w 30a 5v dc-dc psu and you'll see the pic, they all look the same. make sure it says 150w 5v 30a

heres a search list for you:
http://m.ebay.com/sch/i.html?_from=R40&_trksid=m4084.l1313&_nkw=30a+5v+dc-dc+150w
 
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This is what I use in my automotive project. It's an 8v-40v input and 5v 30a output dc-dc ~90% efficient psu, epoxy sealed and weatherproof. It also survives cranking, the lowest voltage I've tested for a drop out is 7.60 volts, however, once the voltage goes back up, it restores the 5v rail, and the voltage doesnt seem to fluctuate either on my DMM.
Enjoy

Also: Cut VIN-VUSB pad (Once you do that, Teensy only works with external power connected), or, option #2, get a data-only usb cable or make your own, by cutting it's red wire

i have used a similar part before but i wanted something smaller and on the pcb this time, also the modules still need input and output protection

good call on cutting vin-vusb

15 V might be a little too low for the TVS -- as the battery goes bad (but not failed), the voltage could approach 15 V -- together with the TVS tolerance, it could cause some current to flow and it might overheat (and not blow the fuse). Try 18-24 V version.

if you care about keeping operation during low battery (e.g when cranking the engine on a cold day), make the input cap larger -- to 1000 uF or more (but watch for the fuse blowing when you connect it initially -- may need a slow-blow fuse). The 78Sxx needs 0.1 uF caps also -- placed close to the chip. If your load current is only 10's of mA or so, it won't need (much of) a heatsink, but if you are driving heavier loads, it might (e.g. 50 mA ==> (14 -5 )*50mA = 450 mW

yes i think i will bump up the tvs voltage

the 5v reg is a switch mode replacement of a linear reg so doesn't need a heatsink. i will need to look into voltage drops when starting and whilst winching tho, it does have a pair of hefty batteries so should be ok and the reg works down to 7v.
 
I've used the LM2940 successfully in the past, it's designed for automotive use and has some cool features built in.
 
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