The PCB layout of power source circuit, this circuit produces course of 3.3 V stabilized voltage from small-sized solar battery. The target in this project is to found very simple, very compact circuit, can think those who be based on small controller is embedded systematic power supply. This circuit is only inside enough illuminative time effective, because should be designed,do not include to be used at the capacitor of energy of memory the rest or batteries.

 

In the article, my general knows the PCB position of circuit from inside graph of power source principle.

 

 

Next graphs indicated PCB coping and bottom position. All component and major mark and copper are pouring be in coping; bottom basically is ground level.

 

 

 

 

 

 

Small controller is the EFM8 Sleepy Bee of Silicon Labs, left (opposite) large connector provides the direct link that debugs adapter with SiLabs USB. This kind of connector wasted space of PCB of quite a few, make integral design is compared it seems that actual bigger.

 

The measure that left a graph to show PCB (with inch for the unit) . Shorter horizontal size is I try to if debug connector to be moved to divide,estimate (arrange afresh with etc component) , circuit board can have many small.

 

 

 

So my guessing is, the double deck of all component of a side board the likelihood is less than 1.5 square inch. I can say this is very pretty good, what discussing considering us especially is double deck PCB.

 

In addition, I use two and I do not think is not 4 and lose any property, because bottom is a strong ground level almost, the ground contact that coping has enough space to be used at wide power supply cord and bounty joins (still will move with low-down frequency because of small controller) .

 

 

It is a few otherer below the method that can reduce this board size:

 

I chose ● bigger passive component IC (0805 and 1206) , because they are assembled more easily. If you plan major to assemble circuit board, you can consider to use 0603 even 0402 (you may be in 0402 acceptability 2.2μF capacitance is found in enclosing, but to 0.1μF capacitance and resistor, you are absolutely and OK use 0402) .

 

● I chose for small controller bigger enclose; the QFP32 that this is millimeter of ×9 of a 9 millimeter. 32 bring a foot to not have bring a foot to enclose dimension apparent smaller (5 Mm×5 Mm) , still have 24 bring a foot to not have bring a foot to enclose, size is smaller (4 Mm×4 Mm) . Look in me, the program of great majority application that proposes around compose of this power source does not need to exceed a few I / O to cite a base, accordingly 24 bringing a foot to enclose a likelihood is optimal choice. I use the 32 parts of an apparatus that cite a base, because this are small,be controller does not have any other down-lead (be not down-lead namely) enclose.

 

● I provided any crystalline substance of high accuracy 32.768 KHz for application of real time clock brace up; the size that it is 0805 component about. Small controller has oscillator of an in-house low power comsumption, precision is very low (±10 ％ ) , if you do not need,time accurately so, you can omit crystal.

 

Manostat of switch of ● charge pump has 4 2.2μF to output capacitance at present, but need only.

 

● LED and its accessary resistor are used at debugging; only they can omit in be designed finally.

 

● you may think to be able to be eliminated with debug all circuit related power source (switch, LDO and two capacitance) . I do not suggest to be done so, because solar energy power supply is not the convenient power source of firmware development and test.

 

 

 

Last when how should make less list are to be in board coping and bottom have package. When I write this article, I begin to suspect whether whole circuit suits the area that answers relatively with solar battery dimension, such circuit that you can design to have coping solar battery and bottom and other thing only board. I decide to delete a few needless component to try this think of a way next from inside principle graph, this is my discovery (dimension with inch for the unit) :

 

 

 

 

 

This is rough approximate, but, you can see, we near the end of the PCB space that a place of strategic importance of will all circuit takes up into the solar battery very much.

 

Place to found this component, I eliminated 3 in 4 output electric capacity, crystal, the resistor of LED and LED. I still hire small controller switch to arrive QFN24. Passive component is remained 1206 with 0805, but these are bigger enclose can make up for you to need some kind of method to join small controller debug adapter. Do not have too much road of course by the space, but if you can use 4 layer board (and the coping of solar battery lower part still has enough space) , I think this is not a serious obstacle.

 

 

The solar energy small controller that we had discussed me to be designed recently board PCB layout, we still studied more the implementation give typical examples that the space optimizes, among them the size that the dimension of PCB approachs a solar battery. If you are embedded to low power comsumption,the space of equipment suffers be restricted to design have any experience, share your opinion in the comment at any time please.