For a project with a tiny PCB (12mm diameter) we want to charge a 470 uF capacitor at 4V. The maximum charge rating for the capacitor is 50 mA. With the capacitor we power a BLE IC (1.8-4V 5 uA).
On your site we noticed a simple charging circuit for a Li-Ion battery, is there a reference design for this to be found? How would we need to adjust it to power this capacitor instead?
Hope to be in contact with anyone who has tried this before and/or an Analog Support Engineer.
The design files of this 6mm solution can be found in this link: https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/DC2769A-A.html#eb-overview
It is possible to charge this 470uF cap at 4V. However, the LTC4124 may have higher quiescent current than this 5uA load. When it is not charging, if you still want to keep the capacitor voltage for a while, you can make the part go into ship mode. You can do that by connecting a diode between VCC and DCIN to make the DCIN voltage higher than 1.5V the moment it is removed from the transmitter.
Hi Wenwei, we have another question. We have a 10mm diameter coil from Würth on receiving side. Do you have experience with transmitter coils being on the same plan but then around it? So a transmitter coil with a 13 mm hole in the middle where the product is in. Not unlike a toothbrush but then the other way around.Hoping to hear your thoughts!
I am not sure what do you mean by 'transmitter coils being on the same plan but then around it'. Could you draw a simple sketch or something to show it?
I mean levelled, concentric antennas, so imagine the transmitter antenna is 15mm and the receiver is 11 or 12 mm.