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Snooze and DPWM of bq500412 EVM

Other Parts Discussed in Thread: BQ500412, BQ500212

Hi,

I have some questions regarding the bq500412 EVM. I recently made a proto PCB referring to bq500412EVM.

But  proto pcb is not working normally . proto pcb has some problems.

I attached the image files regarding following problems.

First problem, 

Snooze signal of proto pcb is always active (3.3V). but Snooze of bq500412EVM is approximately 700 ms pulse signal.

When these conditions appear?

Yellow is EVM pulse wave and Green is proto active wave.

 

Second problem,

Once I removed the Q7 and I made the EN work Forcibly. Vcc is working well. 

DPWM signal of proto pcb is different from the DPWM signal of EVM.

DPWM of EVM is single-pulse bursts approximately every 500 ms.

But DPWM of proto pcb have a different pulse wave form and approximately 2s period.

what is  this problem?

Yellow is EVM wave and Green is proto wave.

 

Finally, I attached image regarding V_SENSE and I_SENSE.

Yellow is V_SENSE of EVM and Green is V_SENSE of proto.

 

Yellow is I_SENSE of EVM and Green is I_SENSE of proto.

I want to know why proto pcb don't working normally.

Making me know how to fix this issues would be appreciated.

Thanks.

 

Best Regards.

 

  • First problem, 

    Snooze signal of proto pcb is always active (3.3V). but Snooze of bq500412EVM is approximately 700 ms pulse signal.

    Snooze and Sleep will removed power from bq500412 by pull 3.3V reg EN pin low.

    Snooze is a 500mS off time between pulse—Set by RC time of R65/C61.  Transistor Q7 will discharge C61 to start Snooze.  C25/R27/D5/R23 will tell the bq500412 that it is waking up from a Snooze, voltage will still be on C25.

    Sleep is a 4 sec off time used for fault condition and charge complete---Set by RC time R64/C60.  Transistor Q6 will discharge C60 to start Snooze.  C25/R27/D5/R23 will tell the bq500412 that it is waking up from a Sleep, voltage will not be on C25.

    Also Q5/C59/R63 is a fast charge for C60 used the first time power is applied to unit.

     

    Second problem,

    Once I removed the Q7 and I made the EN work Forcibly. Vcc is working well. 

    DPWM signal of proto pcb is different from the DPWM signal of EVM.

    DPWM of EVM is single-pulse bursts approximately every 500 ms.

    But DPWM of proto pcb have a different pulse wave form and approximately 2s period.

    what is  this problem?

    If Q7 is removed the Snooze sequence is not working.  After a pulse is sent to Q7 it is expected Power will go away for 500mS then unit will restart.  Power is not going away.

    Try LED Mode 2---Non-low power mode, external Snooze and Sleep are not used.  Change LED Mode resistor to 48.7k.

     

    Finally, I attached image regarding V_SENSE and I_SENSE.

    It is difficult to determine the problem based on the image. 

  • I am using the TI eval module for the bq500412 and see how the Snooze works all right, but I don't see the Sleep mode. I set the LED mode to 4 so no LEDs are on for Charge Complete, which I get. I will be required to pass the energy consumption test from the California Energy Commission (24 hours with all batteries connected) so I am concerned with minimizing current when charge has completed. I am just using a Samsung Galaxy S6 phone at 100% charged, phone off and looking for the Sleep operation but do not see any current saving activity. Could it be a problem with the phone not giving the bq500412 the needed Charge Complete message, or am I missing something?
    thank you
  • The Sleep mode is triggered in response to Charge Complete from the RX, packet EPT01.  This will start the 5sec sleep mode, after waking up the RX will send packet again. 

    If this is not sent the TX will remain on powering the RX.

    Also take a look at the FAQ section "bqTESLA TX Sleep Mode -- RC Time Constant Based"

  • Thank you for the reply Bill. I tried again with a bq51013BEVM and set the jumpers for EN1 and EN2 high and can see the sleep activity.

    But that brings me back to operation with the Samsung phone. Are you saying the phone is not sending a Charge Complete? I assumed it was because when the phone's battery gets to 100%, it turns its Green LED on and the LED_A turns off on the bq500412 eval module (LED mode 4).

    Shouldn't any Qi compatible phone send that Charge Complete message? If not, is there any other way to lower the power consumption after charge has completed?
  • No it does not sound like the phone is sending EPT01, it may be sending some other EPT. I would recommend LED mode 2 it may give you more info on the phone is sending. Note LED mode 2 is not a low power mode but it will hold the LED conditions.

    The phone does not have to send a Charge Complete (EPT01) as part of the Qi certification.
  • Bill,
    I changed out R32 on the eval module to 48.7K to implement LED mode 2. When I charge the Samsung phone, LED_A flashes green until 100%, when it goes solid Green. Isn't that an indication of Charge Complete (EPT01)? If so, it seems the bq500412 does not seem to properly go into Standby mode when I use LED mode 4. Do you have any other suggestions for how to solve this puzzle?
    If you still suspect the Samsung phone is not sending EPT01, do you know of any phones that definitely do send it?
    Thank you
  • Bill,
    I decided to try LED mode 7 so as to get a low power mode and see the red LED for charge complete. I am wondering if maybe I've had wrong expectations about how low the power should go when charge is complete. The data sheet for bq500412 gives a detailed description for idle mode when nothing is on the coils, but does not elaborate about when charge is complete. Should I see the enable line for the VCC go low for short periods of time? If the average power consumption in idle is 160 - 200mW, what do you think I should see when charge is complete? I am seeing about 900mW on the eval module. Please advise if this is within expectations or not, as I do not see any activity on the snooze or sleep circuits.
    thank you
  • Hi Carl
    The Charge complete behavior on the bq500412 (also bq500212) --- after receiving charge complete (EPT01), power transfer stops, green LED turns on for 5 sec and the IC 3.3V remains on during that time. After the first 5 sec LED turns off and IC 3.3V turns off. Every 5 sec the IC will wake up and ping the coils, phone should reply with EPT01 as first packet and the TX turns off for 5 sec then repeats.
    In the case of bq500412 it will try all three coils.
    Take a look at the coils with a scope (Pin 12). What you should see is the three coils ping and then 3.3V turn off for 5 sec.
  • Bill,
    Yes, pin 12 (TP1) is what I've been monitoring. I do not see the behavior you've described, I never see the VCC go off or the DPWM waveform stop for seconds at a time. I do see a change on DPWM when charge goes complete in that the pulses are not as frequent, and there are occasional gaps, but only for a maybe 20 - 30 ms before resuming. If the phone is responsible for all this, I can't figure what it is sending for EPT since the LED_B goes on red as expected for LED mode 7. None of the other definitions for EPT from the Qi standard would seem to make sense for the situation. I was hoping you could cite an example of a phone that you know sends EPT-01 so I could observe the correct behavior?