• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 321 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ24616: About System Power Selector

Tsukui Yusuke
Guru 21930 points
Part Number: BQ24616

Hi,

Customer is investigating System Power Selector switch time.
Please tell us about the following two points.

１．I understand that the breakdown of total switching time is as follows.
　　Is this understanding correct?

　　a. Time to detect adapter current in RAC
　　b. Time required to turn off ACFET
　　c. SLEEP falling shutdown / powerup deglitch time 
       d. Delay time until BATDRV output

2.     "b" and "c" times of the question asked in “1.” are described in the data sheet.
　　 Could you tell me the time of ”a” and ”d”?
　　 
        a. Time to detect adapter current in RAC
        d. Delay time until BATDRV output

Best regards,
Yusuke

  • 0
    TI__Mastermind 24075 points

    Hi Yusuke,

        Input current is being continuously monitored across RAC. The monitoring of input current, is to regulate input current to the whatever value is set for the input current regulation point (equation depends on Vacset and RAC), and once the input current regulation point is reached, the charger will decrease the charge current so as to not overload the input adapter. 

    a. This does not have to do with the system power selector, and is only to regulate the input current. If adapter voltage droops due to overloading, there is no input voltage regulation loop to regulate the input voltage (VINDPM feature in other chargers) and then charger could hit SLEEP threshold, or charger will hit SLEEP threshold due to adapter removal, causing the switch from adapter to battery, to power system.

    d. When the adapter is removed, the system waits until VCC drops back to within 200 mV above SRN to switch from the adapter back to the battery. The break-before-make logic still keeps 10 μs dead time. The ACDRV is pulled up to VCC and the BATDRV pin is set to ACN-6V by an internal regulator to turn on P-channel BATFET connecting the battery to the system. Behavior should be observed on EVM board as datasheet does not have waveform showing this scenario.

  • 0 in reply to Kedar Manishankar
    Guru 21930 points

    Hi Kedar,

    Thank you for your response and support.
    I understand the explanation about "a".
    Please tell me more about “d”.

    〉ACDRV is pulled up to VCC and the BATDRV pin is set to ACN-6V by an internal regulator to turn on P-channel BATFET connecting the battery to the system.
    Customers want to know how long it takes to do the above.
    Is there a design target value for that time?
    If you don't have that information, can you give me an idea of how long it will take to switch?

    Best regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 24075 points

    Hi Yusuke,

       It depends on the R and C components on the ACDRV and BATDRV FETs, as these reduce the turn on time. The dead time is 10us between them to prevent shoot-through, as if ACDRV and BATDRV are on at the same time, this provides a direct path from input to battery. For BATDRV to turn on, first SLEEP condition needs to be hit, where decay of input voltage is a function of input adapter and board capacitance. You can roughly estimate around 2-3ms to 5ms, after ACDRV turning off and BATDRV turning on.

    As this is a controller, the choice of external components plays a factor, and unlike integrated chargers where we have control over the internal components, it is hard to estimate or give a target as it depends on customer board.