Power ManagementのトピックRe: NXQ1TXH5 Compact Charger Design

NXQ1TXH5 Compact Charger Design

bk2001050 — Wed, 17 Jul 2019 21:45:53 GMT

Hi Guys,

I am currently trying to design a wireless solution for a college project with this chip and would like some feedback before I get the PCB made. I have attached a schematic.

Some info:

We are using a transmitter coil with the following characteristics:

I calculated the Capacitance Cp as dictated by the design assistance manual and the rest is identical to the EVM/application schematic.

Couple of questions, how close do the capacitors C3, C4, C5, C6 need to be to the coil, we have mounted all the components on one side and the coil has touch pads on the other side of the pcb.

Does any 10k NTC thermistor work as a thermal sensor?

Is it a good idea to add a fuse to the input of the board as an over current protection device?

Any further thoughts/comments would be appreciated.

Re: NXQ1TXH5 Compact Charger Design

guoweisun — Thu, 18 Jul 2019 02:57:22 GMT

For your questions please below comment:

Couple of questions, how close do the capacitors C3, C4, C5, C6 need to be to the coil, we have mounted all the components on one side and the coil has touch pads on the other side of the pcb.

[gw]There are no specific references,but should be put as close as possible with coil avoid of inducting more parasitic parameters.

Does any 10k NTC thermistor work as a thermal sensor?

[gw]You can use 100K as AN11775 recommend.

Re: NXQ1TXH5 Compact Charger Design

bk2001050 — Thu, 18 Jul 2019 15:21:55 GMT

Hi G.w Sun,

Thanks for the prompt reply. The 100k thermistor was a good catch. Have you had a chance to look at the schematic, I based it on the application diagram, just wanted to make sure all was in order before getting the pcbs made.

Re: NXQ1TXH5 Compact Charger Design

guoweisun — Fri, 19 Jul 2019 01:21:58 GMT

No more issue about your schematic!

Re: NXQ1TXH5 Compact Charger Design

bk2001050 — Tue, 23 Jul 2019 16:04:38 GMT

Hi G.w Sun,

Thanks for your guidance. Quick question, the guide shows a list of coils and their corresponding R8 (Foreign object detection resistance value) but I cannot find a way to calculate this value for a different coil I am using. Is there a formula I could use or am I missing something from the datasheet here? The Tx coil I am using has the following specs:

Re: NXQ1TXH5 Compact Charger Design

guoweisun — Wed, 24 Jul 2019 02:52:45 GMT

We have a App note about FOD configuration,I will send to you!