Hi !
We have a product using the BQ51003 (connected as Fig 3 in SLUA748A) as RX and a Samsung EP-PG920I charging pad as TX. After the first production batch we discovered that some units had problems connecting with the TX. When the matter was investigated it was found that the RX coil had been replaced and that the tuning, thus, had become optimized for 1.5MHz and 170kHz respecively. This should, off course, be corrected, but the real problem is that we cannot understand how the following observations relate:
1. A majority of the devices, with the incorrect tuning described above, works just fine even though the standard specifies 90-105kHz & 900-1100kHz tuning ranges.
2. If the tuning of a "working device" is corrected it still works. If a "non working device" is corrected it still does not work.
3. All devices, corrected or not, work on a different TX pad, i.e. the Belkin F7U014.
I have sent a couple of units back to the manufacturer, for an XRAY inspection of the BGA, in case these anomalies are caused by broken solder joints or soldering shorts. However, this does not seem likely as they do, in fact, work on the Belkin pad.
Since the whole behaviour looks like a communication mismatch between TX and RX we have also tried increasing the COMM capacitors from 22n to 47n. Unfortunately this does not improve anything.
Please advise !
Eric
