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The TI's battery management IC BQ2403x have the chip enable signal which needs to pull up when working. There are four potential power sources to enable this CE signal which are: AC, USB, BAT and System(LDO or OUT) power. However, I think none of them is proper(Maybe I haven't understood this signal correctly).

enter image description here

  • AC or USB or BAT power

None of the three ports must be present when working, user may just use battery or usb or other, so either can be used to power the CE signal alone.

  • System Power

Before the CE is enabled, the system will not get any power, so it can't power the CE signal.

The idea I can have now is to connect AC/USB/BAT power with 'OR' gate to power the CE but I feel it's kind of complicated.Is there any simple way to power the CE signal?

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  • \$\begingroup\$ or gates can always be some common cathode diodes! I'll read the datasheet a bit. \$\endgroup\$ – Luke Gary Nov 23 '18 at 4:00
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Ok, if I understand your question correctly you are trying to determine the proper configuration of the CE pin for your project. From the datasheet: enter image description here From this I can interpret the function of this pin as enabling/disabling standby mode. In this case the chip will not be managing the system power path as well as not charge the battery. If you do not need standby mode you can tie this to a common cathode diode array such as the BAT54C or similar such that the two anodes are connected to either power source. I agree with your closing comments in the question, not too complicated as its a single 3-pin device. I hope this helps!

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  • \$\begingroup\$ Thank you for your answer. It's really helpful to me. \$\endgroup\$ – Ross Nov 25 '18 at 21:31
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Luke beat me to this answer, but here's a diagram from the eval board's schematic that shows the BAT54 diode or'ing the two possible supplies to enable the part. (Assuming you put the jumper in the correct spot.)

enter image description here

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