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BQ2980: Device Operation

TI-CSC
Genius 11180 points
Part Number: BQ2980

Hello E2E Experts,

Good day.

I am developing a new product that will have a plug-pack (wall-wart) as the main power supply and internal battery backup.  My main DC bus will be 5V which will be used to run the unit and charge the internal battery.  If power fails, the internal battery will take over and supply power to the 5V bus.  In this case, the 5V bus voltage will be the battery voltage.

I am looking to use your BQ298xyz device as the battery manager and wish to ask some questions about the operation of this type of device.

This device appears to only limit the current if a preset limit is exceeded.  If that happens, it turns off and stays off.  In my example, if my 5V bus has no separate current limiting, the difference between the 5V bus and the battery voltage will always cause a high current to flow - the current limit will always be exceeded and the charging will stop.  In other words, this device will only work if I have an external current source and the current limit on this device is only there in case of catastrophic failure.  Is that correct?

As I understand it, the resistor setting actually trips out the device.  What I require is to set the charge current to something like 100mA continuous and discharge to allow up to 2A continuous.  A separate trip point says 200mA for charge and 2.5A for discharge.  This cannot be done on one resistor - at least not in this device - as it appears to only have set trip limits and no regulated output.

If that is the case, can you suggest a family more in keeping with what I want?

Regards,

CSC

  • 0
    TI__Expert 8526 points

    Hello,

    Unfortunately, all of our engineers will be out for the holidays.  Our apologies for the delay, and we will get back to you following the vacation!

    Best,

    Andria

  • 0
    TI__Mastermind 37750 points

    Hello CSC,

    If you have no dedicated charger and are not limiting the current, then yes it is very likely that the protections will be triggered. This device does not limit the current, it just cuts-off the current completely if a fault is detected. The thresholds can only be changed with the sense resistor based on the trigger points, you can see the available devices in Section 5 Device Comparison Table of the datasheet.

    The protections and recovery conditions can be found in Section Table 8-1. Device Configuration Range of the datasheet.

    For single-cell protections, this device may be the best option there is.

    Best Regards,

    Luis Hernandez Salomon