Direct question for NXP support engineers unless someone else out there has already successfully used the NXQ1TXH5
Hi, I have a new board design using the NXQ1TXH5 and I have followed the datasheet and app note 100%. Unfortunately I have problems that I cannot diagnose:
1. Generally, the power transmitter starts up if the battery is low charge but when charging is complete or almost complete (difficult to determine this), charging stops and I get a flashing LED indicating a fault condition. I cannot diagnose which fault this is but I have to assume it is a receiver error, as it cannot be FOD or overtemperature (temp is low and power consumption is less than 1.5W). At this point, switching frequency is approximately 150kHz.
2. I have the NXQ1TXH5DB1401 eval (demo) board, and it will not start power transfer at all, and displays the flashing fault LED after attempting to establish connection for a few seconds.
In both cases I am powering directly from a 5V 2A lab power supply and am monitoring current, which is initially 800mA, and drops to 250mA or lower before cutting out.
3. There is an I2C interface on the chip which is described as "for assistance by NXP Semiconductors". Can the I2C interface provide log or diagnostic data to explain which fault condition is causing the problem? Please provide me with any necessary software and details of the I2C adapter I need to use.
4. My design uses small size 30mm coils from Wurth (Tx http://katalog.we-online.de/pbs/datasheet/760308101103.pdf , Rx http://katalog.we-online.de/pbs/datasheet/760308103205.pdf ). I have so far used the NXP demo board only with its standard large coil but I will also check with the 760308103205 Rx coil.
5. The design of our receiver (which uses BQ51013B receiver), when charging is complete, by-passes the battery so that the Qi receiver provides power directly to the hardware, and the battery is open circuit. The hardware switches between standby and operating modes, with approximately 80mA current pulses for a short time (tens of ms) - it is necessary that the Qi transmitter must continue to provide power all the time, and I expect trickle charge mode to support this. The datasheet says in "8.1.6 Charged state and trickle charge" that "When the NXQ1TXH5 receives a ‘charge status 100 %’ package (CS100 package) from the receiver, it changes the LED indication to charged state, but continues to operate in power transfer state". We already successfully do this with off the shelf USB charger pads.
Can you please help?