HI bzyzny.
R11, R12 (AP3417C - U5) and R13, R14 (AP3417C - U6) are supposed to be in 'K' values, you have them in the schematic in ohms.
As a general rule, we prefer to purchase fixed switching regulators that are not dependent on the external resistor voltage dividers. The key reason being that if either of these external resistors are not soldered properly or wrong value then this could lead to killing all powered devices downstream. The board will then be scrap. When not avoidable, we prefer to use larger sized resistors for such tasks (ie. 0603 or 0805 footprint) and we still visually inspect the assembled boards before powering up. We have a very high quality assembly shop who has automated vision equipment to confirm the part placements and values during production.
Share the details on the L1 and L2 inductors as they are not all equal to be sure the proper footprint is placed on the PCB. Many such parts will derate their inductance as the current draw increases so be sure to check the respective datasheets to make a valid selection. We have good luck with Taiyo Yuden. For example, consider p/n NR4018T2R2M which is available through Digikey.
http://www.digikey.com/product-detail/e ... ND/1008284
What are the details of Y1 ? Size ? Part number ? In assembly, you will pay for each part placement so need to consider if it makes sense to stuff the 6 parts to create a 24 Mhz oscillator or stuff a single SMD oscillator for the same task. With some creative shopping it may be less expensive to purchase the SMD oscillator. For example, you should be able to source a single SMD oscillator @ $.28 to $.30 USD each from WTL Crystals in Shenzhen China. We have used them quite often now with zero defects. Just a suggestion. From our last feedback from this supplier, the 3225 SMD footprint was the most popular to apply due to the cellphone markets. Smaller footprints are also available on demand at higher costs. 3v3 operation and 30 PPM. However, it is possible to source the 3225 (crystal) @ $0.08 to $0.12 USD each, varying with the PPM accuracy from the same vendor.
Be sure to review this article on how capacitance varies with voltage and size of the parts:
https://www.maximintegrated.com/en/app- ... vp/id/5527
before selecting the bulk caps in this design. We found that Samsung appears to be the most competitive and have consumed very high volumes with success for many years. Check Avnet (preferred) and Future Electronics (sometimes lower cost but need to offer the comp pricing) for competitive pricing.
It appears that you will not be using USB data pins in this design. If you do, must apply ESD protection devices (Socay, Shenzhen, China) to prevent ESD damage to the controller. We have some pending designs that will use the USB interface to power the end product and plan to permit the use of the ultra low cost power supplies from China that are AC to 5 volt out via USB. To prevent damage to the 5 volt power supply parts on your board, we have over voltage supply limiters in case the 5 volts in is not within spec. This is very possible to support using a part like the USB load switch (select the proper current for the respective switch for this project).
For the USB connector, review how the board locks work for the part to allow for the best physical mounting strength. It will not be desirable to have the end user rip this connector off the PCB during insertion. For our designs, we are planning to use the FCI 10118194-0001lf component which is available through Digikey, Mouser, etc. and is supported by a large and solid manufacturer. We did import some USB connector parts from China at half the cost but the quality was not up to our standard - fit was loose and had to toy with the mated connectors to have a solid connection. Garbage.
What are the details for P1, P2 and P3 ? Through hole (vs. SMD) are the best choice here for best mounting strength.
We have an excellent supplier for such parts and are the real manufacturer, not a trading company. They deliver most goods made to our spec within 5-7 business days. Costs cannot be matched by other suppliers.
For these metal stamped parts:
Contact: Jane
SHENZHEN JINLING ELECTRONICS CO.,LTD.
Address:E Building,YuSheng Industrial Park,,Beside ZhouShiRoad,JiuWei,Xixiang,Bao'an District,Shenzhen,China
Http:www.szjiln.com
Email:
jane@szjiln.com/
janeszjiln@gmail.com
Cell:+86-13632524786
Tel:+86-755-29975806 Fax:+86-755-22975992
You can decide on the amount of gold plating, length of the pin before and after the insulator, the thickness of the insulator, etc. This company has also produced our 2 mm pitch parts for our High Def PCIe host adapter and we switched away from Samtec to this vendor with success. Perfect quality. They also offer the keyed box header which is recommended for the XSYS connector.
You may not need the on/off switch but if you do, what are the details ? Details of the manual PB for reset (SW1) ?
Perhaps add a small (0603) LED with a current limit resistor to denote power ? Cannot use the 1v0 rail due to the low voltage for the LED. With a bit of thought, could use a few parts to enable the same LED only if the 1V0 rail is enabled. Perhaps another LED (green) on the project board to allow for the end user to create a quick blinky demo ? This LED could then be disabled to remove from the circuit.
Prices for standard RGB leds are falling in Asia. We have received offers for the SMD RGB leds in the $0.014 to $0.03 USD range.
Kumar