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Part Number: BQ51003
We are using Wireless charging IC BQ51003. Our device is designed for 500mA and the ILIM is 330 ohms. Without connecting load,the voltage at Vrect is 6.5 - 7 V and Vout is 5v. When connecting the load of 10 ohms at Vout of wireless charging IC there is a voltage drop at Vrect and Vout,the measured voltage at Vrect is 3.6V and Vout is 3.3 - 3.5 V. This same occurs when we change our device for 350 mA and ILIM for 560 ohms. But when we change our device for 250mA and ILIM for 845 ohms,there is no voltage drop at Vrect and Vout during the load condition.what will be the reason for the voltage drop when designed for 550 mA and 330 mA. We need our device to be work at 550 mA.
What can you tell me about your RX coil and tuning?
Also what value FOD resistor are you using, FOD pin gnd?
Bill Johns, Applications Engineer
Texas Instruments Inc
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In reply to Bill Johns:
RX coil WR222230-26M8-G
FOD pin is connected to Microcontroller
In reply to Jagan K:
the FOD pin needs to be connoted to ground thru R-FOD, see figure 32 in data sheet. The RX will report received power as a function of output current, ILIM current develops a voltage across R-FOD. This is converted into a digital value sent to TX.
WR222230-26M8-G coil is small and will work well below 500mA. Resonant caps need to be tuned to about 100nF.
Thanks Bill for your idea.
Actually we need our device to be worked in 500mAh current,is there any schematic for BQ51003 to work in 500mAh.
Some designs that can be used as a reference:
1.) Evaluation board -- www.ti.com/lit/pdf/sluuau8
2.) TI Reference design TIDA-00318 -- www.ti.com/tool/TIDA-00318
3.) TI Reference design TIDA-00669 -- www.ti.com/tool/TIDA-00669
Thanks Bill Johns for your reference
Can we keep the FOD as floating(i.e not connected)?.
Floating FOD will cause problems.
Need to connect to ground thru resistor and resistor between ILIM and FOD, see application section of data sheet.
We have designed a device with wireless charging technique using Bq51003 and receiving coil WR222230-26M8-G.In the above configs we are facing some problems while charging.
One major issue is that charging stops suddenly for more-than 10mins and it continues to charge after that time,what maybe the reason?.
While testing we are removing and placing our device in the charging pad for multiple times,after this testing it stops charging for 5 mins.can i know the what is the reason?
Also i have to know the above kind of testing will cause any damage to the components?
Temperature rises up-to 60 deg Celsius while charging,is there any possibility to reduce the temperature?
I too have same problem,when we test our device in charging pad ,charging stops suddenly and it takes some time to recover.Can some one suggest what could be the solution?
What must be the minimum voltage rating of capacitor C1 C2 in the input side of bq51003?
In evaluation kit they used three parallel capacitor in the input,shall we use one capcitor in that place instead of three capacitor?
Bill ,what is FD and Fs and Ls and Ls' in C1,C2 calculation?
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