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BQ24075: Charge current does not get to expected levels

Eliran Amar
Prodigy 10 points
Part Number: BQ24075

Using a Lithium Ion battery and the BQ24075 battery charger, when power is supplied, the charging current does not get to the expected level. I have the EN1 and EN2 pins configured for "Set by external resistor between Ilim to VSS" charging limit by using software from microcontroller (EN2=High, EN1=Low), SYSOFF and CE are driven low to enable charging. 

When a charger is plugged in, the charge current is ~400mA.  The battery is being charged, but at a much slower rate than expected 1.5A.

See Schematic:

Thanks in advance,

Eliran.

  • 0
    TI__Guru* 75786 points
    Hello
    Some things to check:
    1.) Check the Voltage at BAT with a scope, if you see a low freq square wave it could be the battery detect circuit tripping.
    2.) Unit has Input -Based Dynamic Power management, If input voltage is reduced the charge current is reduced
    3.) If resistance is added in the battery output path it will reduce point where unit enters voltage regulation, check voltage at BAT.

    Resistance in the BAT to battery path can cause a couple of problems, the fuse DCR should only be about 100m ohms should not be a problem. But if it is high and other resistance is in the path is could cause battery detection issue.

    Input current will be high and voltage drop on the input could reduce the input voltage and trigger DPM function.