NXQ1TXH5 CNF_IN and LED Red/Green not working

cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

NXQ1TXH5 CNF_IN and LED Red/Green not working

926 Views
labib
Contributor I

I have made a custom PCB board with an NXQ1TXH5. Wireless charging is working, however at quite low current being supplied to the receiver coil. Investigating the board shows that CNF_IN goes between VDD (~5V rail) and 0V, even though the resistor network is present and should work as a potential divider.

I have been following the app note AN117755 and have varied the resistance values of CNF1-4 which has resulted in absolutely no change in the response of CNF_IN. It continues to pulse to 0V from VDD every ~3secs. 

As a result I cannot set the LED Mode and therefore have both Red and Green floating. Anyone seen these issues before on CNF_IN and/or LED Red/Green?

Labels (1)
0 Kudos
3 Replies

783 Views
reyes
NXP TechSupport
NXP TechSupport

Hi,

Are you using the Static Power Reduction feature of the NXQ1TXH5? It seems like you do because your comments match with the operations of this feature (limits the supply current, CNF_IN is sensed every 3s (while CNF1 is low)).

 

Please measure the voltage directly on VCNF_IN pin when CNFG1 is active to make sure you are getting the desired voltage on this pin.

Take in mind that to detect if the SPR setting via the CNF1 pin has changed and the NXQ1TXH5 limits its power consumption accordingly, the CNF_IN pin is sensed every 3 s after start-up NXQ1TXH5.

 

Please check the details on section 2.1.3.1 of the AN11775: https://www.nxp.com/docs/en/application-note/AN11775.pdf

0 Kudos

783 Views
labib
Contributor I

Thanks I understand the waveform I'm seeing a lot better now although the LED lights are still not working.

Below is the response I got on the oscilloscope. Yellow waveform indicates voltage on CNF1 pin and Purple waveform indicates CNF_IN pin. 

From this I gather that VSPR >1.335V (@2.540V)and therefore SPR is OFF and SPL is ON

tek00001.png

0 Kudos

783 Views
reyes
NXP TechSupport
NXP TechSupport

Hi,

LED uses NCF4 pin to operate, which measure the voltage on the CNF_IN pin while CNF4 is low.

Depending on the CNF_IN pin voltage (when CNF4 is active) and the value of the resistor “R10”, is the operational mode of the LEDs. Check section 2.1.3.3 of the AN11775 for detailed information.

0 Kudos