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BQ25155: entering and exiting ship mode without a mechanical switch

pragash sangaran78
Genius 3510 points
Part Number: BQ25155

We are designing with the battery charger chip above, trying to make use of the ship mode for our Li-Poly battery. 

1) We are a battery-powered device. If MCU program battery charger to enter ship mode, the whole circuit will be turned off, including MCU. Can the program be successfully executed before the MCU goes to shut down!

2) we program the product in the factory into ship mode. When the customer gets it, they have to bring it out of ship mode! Any example of the circuit to accomplish this? As I stated above, we don't have a mechanical switch, so please advise other methods to bring the circuit out of ship mode. 

  • 0
    TI__Mastermind 21590 points

    Hello,

    1) What program are you concerned about not being executed? If the device turns off after shipmode command is sent, the command has been executed. The MCU can pull /MR low through a FET  before the shipmode command is sent. This way, the MCU can release /MR after all programs have been executed. 

    2) One of the ways to exit shipmode is through a VIN plugin or by using a pushbutton. Is there any other way the user can let the device know to exit shipmode>

  • 0 in reply to Raheem
    Genius 3510 points

    1) What program are you concerned about not being executed? If the device turns off after ship mode command is sent, the command has been executed. The MCU can pull /MR low through a FET  before the ship mode command is sent. This way, the MCU can release /MR after all programs have been executed. 

    My answer: the program that I concern not being executed is the command to enter into ship mode. Is it even possible? Because when MCU program the charger to enter ship mode, the battery gets disconnected and the entire system goes shutdown. Will the command have enough time to properly executed? 

     

    2) One of the ways to exit ship mode is through a VIN plugin or by using a pushbutton. Is there any other way the user can let the device know to exit shipmode>

    my answer: this is great if just by plugin the VIN, the device can be recovered from the ship mode. Any example circuit to accomplish this? I know the datasheet of BQ25155 has a configuration of the mechanical switch at MR to bring the circuit out of the ship mode. 

  • 0 in reply to pragash sangaran78
    TI__Mastermind 21590 points

    Hello,

    !. The system shutting down means the command was properly executed.

    2. There is no circuit. All you need to do is provide 5V on IN and the device will exit shipmode.

  • 0 in reply to Raheem
    Genius 3510 points

    I have one last question. Since there is no mechanical switch at MR, I think I need to connect MR to MCU GPIO because it will help charger to enter and exit ship mode.

    there are two methods to enter ship mode;

    1) When EN_SHIPMODE = 1 and IN supply is removed, the Device will enter ship mode. 

    2) If MR pin is held low when EN_SHIPMODE is programmed to be 1, the Device will have to wait until the MR pin goes high before entering ship mode. 

    Let's think about from the customer perspective. The device enters ship mode at production via method 1) and goes to the customer's house. The customer connect the device to DC power supply at VIN, and the device comes out of the ship mode. Since this is a wearable device, customers have to disconnect the device from the DC power supply. when they do that, the device enters ship mode again which is a disaster!

    If we program the device to enter ship mode using method 2), when customer connects the device to DC power supply, we will have the default program for MCU with MR = 0V, so the device stays ON even after the DC power supply is removed. 

    Correct me if I'm wrong. 

  • 0 in reply to pragash sangaran78
    TI__Mastermind 21590 points

    Hello,

    You dont want to connect MR to MCU GPIO because /MR is pulled up to VBAT and that voltage could damage the GPIO pins.

    3) You can also enter shipmode through a long button MR press by configuring the MR Long press action bit in register 0x36.

    Let's think about from the customer perspective. The device enters ship mode at production via method 1) and goes to the customer's house. The customer connect the device to DC power supply at VIN, and the device comes out of the ship mode. Since this is a wearable device, customers have to disconnect the device from the DC power supply. when they do that, the device enters ship mode again which is a disaster!


    This is NOT correct. After the customer plug in VIN to exit shipmode, the device stays active even after VIN is removed.

    If we program the device to enter ship mode using method 2), when customer connects the device to

    DC power supply, we will have the default program for MCU with MR = 0V, so the device stays ON even after the DC power supply is removed. 


    Also incorrect. you dont need to hold /MR down to stay out of shipmode after VIN is removed.