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USE BQ51025-EVM to output 5V 2A with BQ500215-EVM

eiven wu
Prodigy 215 points
Other Parts Discussed in Thread: BQ500215, BQ51025, BQ501210

Dear,

i  use the BQ51025-EVM to output 5V 2A with BQ500215-EVM.I had changed some components on BQ51025-EVM.

 If i put the RX-EVM on center of TX-coil,it can not work well.

i need to shift a little location,and it can work well.

if i change the resonance capacitance of BQ500215 from 0.247uF to 0.315uF,It had work well on any location.

but I use BQ51013B-EVM on BQ500215-EVM,It only work well on center of BQ500215-EVM.

could you help to fix this issue of 5V 2A application?

 

thanks.

 

  • 0
    TI__Guru 65846 points
    Hello
    The changes from standard 7V configuration to 5V configuration will require several changes for satisfactory performance. I have compiled a list of changes and will post them is a separate email.
    For 5V operation two voltage dividers need to be changed. Also the 7V coil will not work well at 5V and the coil needs to be changed.
    To help diagnose the problem you are seeing please check RECT TP3 in both centered (bad) and offset ( good) position. During communications packet we expect to see a dip in voltage at good coupling the dip in voltage may be too high.
  • 0 in reply to Bill Johns
    TI__Guru 65846 points
    To change the standard 7V bq51025 EVM to 5V several parts need to be changed.

    1.) Vout
    • Set by R18 / R10, for 7V 130k / 10k for 5V change to 100k /10k
    • This will set voltage to 5.5V, this will help with voltage drop though lead
    • For exactly 5.0V use 102K, 11.3K
    2.) VIREG
    • Set by R19 / R12, for 7V 130k / 10k for 5V change to 100k /10k
    • This will set voltage to 5.5V, this will help with voltage drop though lead
    • For exactly 5.0V use 102K, 11.3K
    3.) Iout
    • Output current set to 7V at 1.4A, R4 237, R2 + R6 256 (ADJ)
    • Change R4 from 237 to 110 ohms
    4.) FOD
    • 7V FOD set by R17 150k, R2 + R6 256 (ADJ)
    • Change R2 + R6 from 256 to 254, adjust R6
    • Change R17 from 150k to 100k
    5.) Coil
    • Vishay IWAS4832FEEB150J50 (7V—15uH), not recommended for 5V
    • Change to Wurth 760308201 (5V—10uH), but check thermal performance at max load.
    • Or Change to Wurth 760308102207(5V—8uH), but check performance with 5W solution if required.
    6.) Coil Tuning
    • Change C3 82nF and C1 47nF
    • For Coil 760308201---C1 + C2 +C3 -- 206nF total
    • 760308102-207—---C1 + C2 +C3 -- 239nF total
    • Capacitors should be COG or NPO type with 50V or greater rating.
  • 0 in reply to Bill Johns
    Prodigy 215 points

    Dear ,
    i had used the conditon of your suggesent.Vout=5.5V.
    i use coil of 760308201,and Cs are 211nF.
    It can not work on center and the TX and RX distance can not over 2.34mm.

    Please refer the below of picture

    picture 1 is bad.

    picture 2 is good.

    ther are test on distance=2.34mm.

  • 0 in reply to eiven wu
    TI__Guru 65846 points
    Output current BAD is only reaching 1.1A while output current good is reaching 2.0A.
    The problem may be the system operating in a 5W vs 10W mode.
    When the bq51025 RX is placed on the bq500215 TX the green LED will flash.
    5W mode---Slow flashing of LED
    10W mode---Fast flashing of LED

    When the RX is placed on the TX it will identify itself as a 5W or 10W RX---something could be going wrong with this handshake when the unit has good coupling
  • 0 in reply to Bill Johns
    Prodigy 115 points

    I modified above said for bq51025 5V/2A and with transmitter by BQ501210 (Q1.2, 15W)

    But the bq51025 output just 5V, 1.2A. It can not reach on 10W(5V, 2A) 

  • 0 in reply to user4104025
    TI__Guru 65846 points

    On the bq501210 TX try removing shorting jumper JP1. This will disable the FOD function that may be limiting the power to the RX, treating it as a 5W device.

    Note this change will only be detected at power up of the TX, cycle power after removing or installing the jumper.