Why don't you provide power to the FAN5331SX directly from the battery? It can accept voltage range from 2.2v to 5.5v. That way you eliminate a good portion of the loss of efficiency of the linear regulation, and you will also need less filtering on the output of the linear regulator.Battery (3.7 V) linearly regulated to 3.3 V provides VDD. Vdd for logic is then boosted to ~18 V using a boost converter (FAN5331SX) to provide Vcc.
It looks like you have some pretty long traces from the OLED connector to the 24 pin dual header. Can you move them closer together to reduce their length?The OLED has a FPC ribbon with contacts having a pitch of 0.75mm, which I created a package for in EAGLE with the smd pads.
It will work, but that trace seems to be quite long, and rather thin. I don't know how much current you're planning on it conducting. You should run your numbers through PCBtemp to find out how much thermal rise you're going to get with the trace widths you're using. Roman Black is hosting PCBTemp, as UltraCad has dropped support for it:Things I dont get:
-To get Vcc to the oled pads, I've had to use a via and route it from the bottom. I don't think this is elegant, but will it work?
Whenever you need to route a signal from one layer to another.-When are you supposed to use via's? I basically just used them when I ran out of space on the top layer?
You used the horizontal package. Use the vertical package.-Why does the LM1117T get printed out on the silkscreen layer when it will be 'standing up'?
Sure.- For the Ground plane. On a 2 layer board, are traces at the bottom still acceptable?
Have a look at this page:- Can anyone recommend resources on PCB design ?
If the LM117 is like the more common LM317, it can't regulate 3.7V to 3.3V. It has a minimum voltage drop of about 1.3V. Also it looks as if it's not wired up right: am I seeing the ADJ terminal connected to Gnd, and two resistors going from Vdd to Gnd and never touching the ADJ pin?
There should be a filter capacitor as near as possible to the power supply terminals of the processor.
There should be an electrolytic capacitor between Vbat and Gnd.
How about part numbers on the silkscreen?
Is that long row of pads in the bottom right intended as a connector? You'll need to have a gap in the solder mask to expose them, and it seems as if some of them are shorted. Those are very small pads, if that's what they are!
Please don't say you designed this on the fly and never drew a circuit diagram!
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by Jake Hertz