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BQ25120: BQ25120: clarification on the mask bits for MR and the HIGH-Z mode

Anthony Dobaj
Prodigy 230 points
Part Number: BQ25120

Some clarification on the WAKE_M and RESET_M fields of the mask register. If these bits are asserted, does that mean that the associated function of the MR pin is disabled? In other words, if you set the WAKE_M bit then asserting MR will not take you out of ship mode? Also, can you clarify the HIgh-Z mode, paragraph 9.3.2? In high impedance mode, are the switcher and LDO actually regulating (off the battery)? the first part states 

"During Hi-Z mode
the SYS output is powered by BAT, the MR input is active, and the LSCTRL input is active. All other circuits are
in a low power or sleep state.The LS/LDO output can be enabled in Hi-Z mode with the LSCTRL input. If the
LS/LDO output has been enabled through I2C prior to entering Hi-Z mode, it will stay enabled". 

This implies that the SYS output and LDO are running off the battery. BUt then it says:

The CD pin is
used to put the device in a high-impedance mode when battery is present and VIN < VUVLO. Drive CD high to
enable the device and enter active battery operation when VIN is not valid. 

What is "active battery operation" exactly? Thanks for the clarification.

  • 0
    TI__Genius 12485 points
    Anthony,

    Exiting the Ship mode will always work ir-respective of the register setting. During Ship we turn off all the digital blocks to go to the lowest power state.

    In this state we check for MR and VIN. If one of these activities were to happen, we exit Ship mode.


    The active battery operation will let you configure I2C, control registers, read VBMON etc., Assume Active Bat as the chip being completely responsive and ready to take action. From my experience where most of the systems run until ~30% of the battery life.

    To get lower power consumption- say when the product is not "ON" to the user, you could put the device in High-Z mode. Where the system is still running or your product is counting clocks etc., but at a very low power state.

    Hope this clarifies.

    Regards,
    Gautham
  • 0 in reply to Gautham
    Prodigy 230 points
    Hi Gautham, ok, thanks for that info. So exiting ship mode with MR always works, great. So those mask bits are only for the pushbutton timer functions (wake1, wake2 and reset)?

    The nature of my question about high-z mode was not so much about the functionality available on the 25120 but rather what is powered by the 25120. So I'm using the internal (to the 25120) regulators to power different aspects of the system. I understand that in High-z mode, the MCU cannot talk to the 25120, but are the regulators working? When you say "product is not "ON" to the user" I presume you mean our product, but the user interface for our product is only "ON" if the regulators are working. When you say the "system is still running" do you mean the regulators are functioning? And when you say "at a very low power state" do you mean the regulators are running but current limited? Thanks again.
  • 0 in reply to Anthony Dobaj
    TI__Genius 12485 points

    Anthony,

    Regulator as in VSYS and LDO? then yes- they both are running in both states. :)

    regards,

    Gautham Ramachandran