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Linux/BQ25890: BQ25890

carleen chen70
Prodigy 110 points
Part Number: BQ25890
Other Parts Discussed in Thread: AM4378

Tool/software: Linux

Dear Sir,

We use BQ25890 in our board for battery charge and its output SYS1 and SYS2 is our main power supply SYS (V3.0). The problem is when we power on, after a few seconds (10 or more seconds), it goes to low and after 500 ms, it goes high again. If we don't connect any load, then it doesn't go to low. We don't know if we need to configure its registers or there is a default function to reset. We pullup CE pin (disable battery charge), but it is no help. Please help.

Thanks.

4061.BC4_Page15.pdf

Carleen

  • 0
    TI__Guru**** 167196 points
    Carleen,

    How much is your load on SYS? Is your input current limit register and ILIM pin resistor set to provide input power for your system load? Have you disabled the ILIM pin using the EN_ILIM bit? Are you pinging the watchdog timer bit?
  • 0 in reply to Jeff F
    Prodigy 110 points

    Hi Jeff,

    We don't touch registers yet. Everything is default setting. If it is necessary to set the registers, then when and where can we do when we boot the system (power on)?

    Thanks.

    Carleen

  • 0 in reply to carleen chen70
    TI__Guru**** 167196 points
    Carleen,

    The charger operates in default mode until the host writes to the registers. In default mode, the ILIM pin resistor clamps the input current. If you do not have enough input power, the SYS output will drop to the battery voltage and the battery will supplement the system load. What is your system load?
  • 0 in reply to Jeff F
    Prodigy 110 points
    We pretty sure our load is not very big . There is only a AM4378 processor and 1GB DRAM. we don't connect other devices yet. The problem is it is down to 0V. If you say it down to battery level, it'll be ok. We tried to use a 100 ohm resister in ILIM, but it is same. We tried to remove L between SW and SYS1 & SYS2, but it is same. Please help.
  • 0 in reply to carleen chen70
    TI__Guru 57831 points

    Carleen,

    Please note the spec below on the d/s. The input current limit is set to 200mA internally until VSYS rises above 2.2V.

    Thanks!

    Please click "This Resolved my issue" button if this post answer your question.