Datasheet

bq24100, bq24103, bq24103A

bq24104, bq24105, bq24108, bq24109

bq24113, bq24113A, bq24115

SLUS606O –JUNE 2004–REVISED MARCH 2010

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Precharge: The current is low in precharge; so, the bottom synchronous FET turns off after its minimum on-time

which explains the step between Ⅹ0 V and -0.5 V. When the bottom FET and top FET are off, the current

conducts through the body diode of the bottom FET which results in a diode drop below the ground potential.

The initial negative spike is the delay turning on the bottom FET, which is to prevent shoot-through current as the

top FET is turning off.

Fast Charge: This is captured during the constant-current phase. The two negative spikes are the result of the

short delay when switching between the top and bottom FETs. The break-before-make action prevents current

shoot-through and results in a body diode drop below ground potential during the break time.

Charge during Voltage Regulation and Approaching Termination: Note that this waveform is similar to the

precharge waveform. The difference is that the battery voltage is higher so the duty cycle is slightly higher. The

bottom FET stays on longer because there is more of a current load than during precharge; it takes longer for the

inductor current to ramp down to the current threshold where the synchronous FET is disabled.

Product Folder Link(s): bq24100 bq24103 bq24103A bq24104 bq24105 bq24108 bq24109 bq24113 bq24113A

bq24115