A charger adapter to provide a USB-C interface to some of the following products
- Braun
- Oral-B
Or any other simple 12V charger that consumes less than 500mA. Check your charger or device manual for compatiblity. Generally, these are shavers, epilators, electric toothbrushes and similar products. This provides a small convinent charger that can be convinently be stored in along with the toothbrush in its own travel case. Also, it lets you only bring a single charger and cable with you on your travels for all your electronics, letting you pack lighter.
This twitter thread can provide background and further updates.
This is still in Alpha and has not been tested. Please wait for 1V0 Relese candidate or continue at your own peril
One was assembled and works with non PD chargers, I think I have quite a few bad solder joints on the USB-C connector, I'll be testing again with a cleaner paste application with a stencil. Upgraded to Beta.
The stock charger provided with my Oral-B Genius 9000 travel case is rated at 12V and 400mA. The design will be set to match the voltage and exceed the current requirements, so it works with as many similar porducts as possible.
Using the USB 5V avalibilty as more adapter suppourt rather than the 15V and boosting the voltage to 12V from the 5V@3A would provide 800mA with perfect efficency letting us rate our charger safely at 500mA. The 12V profile is also being completely avoided since the 12V profile only existed in the REV 1.0 of the power delivery protocol and is not compatible with current standards. Using the 5V profile also allows us to not need a negotiator and instead just use two passive 5.1K resistors on the CC lines.
The Microchip MIC2290 is a easy to implement boost converter with a intergrated switch and didoe requiring only external passives. A 10uH inductor, some input and output capacitors and resistors to set the output voltage are all that are needed. The 43.2K and 5k resistors are from the example in the datasheet to set the voltage to 12V.
The bill of materials is availible in bom.csv and is copied into a table below.
| Ref Des | Qty | Manufacturer | MPN | Description |
|---|---|---|---|---|
| C1 C2 | 2 | Samsung | CL21A106KOQNNNG | CAP CER 10UF 16V X5R 0805 |
| J1 | 1 | Amphenol ICC | 12401610E4#2A | CONN RCP USB3.1 TYPEC 24P SMD RA |
| L1 | 1 | Taiyo Yuden | NRS5030T100MMGJ | FIXED IND 10UH 1.7A 70 MOHM SMD |
| R1 R2 | 2 | Yageo | RC0402JR-075K1L | RES SMD 5.1K OHM 5% 1/16W 0402 |
| R3 | 1 | Yageo | RC0402FR-0743K2L | RES SMD 43.2K OHM 1% 1/16W 0402 |
| R4 | 1 | Yageo | RC0402FR-074K99L | RES SMD 4.99K OHM 1% 1/16W 0402 |
| U1 | 1 | Microchip | MIC2290YML-TR | IC REG BOOST ADJ 750MA 8MLF |
A Octopart BOM is also availible to simplify ordering.
Assembly is all surface mount with componets on one side of the board to make PNP assembly easy.
Solder paste can be applied with 26ga+ syringe, or with a stencil of the top paste layer, and then reflowed. The componets can then be placed, taking note of the two that are polarity dependent being U1 and J1 as marked in the assembly layer.
Then a connector from a charger can be removed and after checking polarity, soldered on to the two though hole pads denoting 12V and GND.
I havent tested the exported gerbers fully, I just upload the KiCad file. The board will be a standard 1.6mm (0.063") two-layer FR4 with 6/6mil spacing, plated though vias. These are generally the defaults boards so they can be made by most fabrication houses.
PCB Dimensions
| Width | Height | |
|---|---|---|
| Inches | 0.48 | 0.75 |
| mm | 12.1 | 19.1 |
At OSH Park 3 boards will cost 1.75 USD. This includes shipping internationally. Components not including the Braun connector come to 3.46 USD at Digikey. These are all in low quantity.
