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I am looking to implement the bq24075-Q1 (datasheet) for a school project. This IC can charge a LiPo while simultaneously proving power to the system. The Absolute Maximum ratings sais that the maximum output current is 5 Amps and the maximum charging current is 1.5 Amps. Would I be correct to assume the following:

1) If my system has no battery connected the bq24075-Q1 can pass through 5 Amps to my system.

2) If a battery is connected and charging at the max rate the bq24075-Q1 can pass through 3.5 Amps to the system while still charging the battery at 1.5 Amps

3) There is no current limit on the "OUT" pin. Imagine if the "IN" current can provide a max of 3 Amps (say that is the limit of the wall-wart) and the battery is fully charged. If the System tries to draw 6 amps what will happen? Will 3 Amps be sourced from the "IN" pin and 3 Amps from the "BAT" pin and the IC will overheat and fail?

Thanks in advance for your help!

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1) No. The maximum input current is specified as 1.6 A (just look directly above the lines you have marked). Since this the absolute maximum, you should not draw more than 1.5 A from the input (the recommended current limit). There is also a (configurable) current limit to ensure that.

2) Yes and No. See above - the input is limited to 1.5A. The bq24075 has the feature of power distribution, so it will try to supply your circuit with the power it needs, and use the rest (up to the 1.5 A input current limit) to charge the battery. If the curcuit draws too much current, the battery won't be charged.

3) 5 A is the absolute maximum the bq24075 can deliver safely on its output (and the recommended operation conditions states 4.5 A as the limit for normal operations). If your circuit can draw more than that, it can (and possibley will) damage the bq24075. There is no battery current protection (see page 18 in the data sheet), except for short circuits (see same page). Note that the 1.5 A limit for the input still holds, so the battery needs to deliver more than 3.5 A to reach the limits of the bq24075.

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