BQ24188_15 Datasheet, PDF (41/52 Pages) Texas Instruments – bq24188 2A, 30V, Host-Controlled Single-Input, Single Cell Switchmode Li-Ion Battery Charger with Power Path Management and USB-OTG Support

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11 Power Supply Recommendations
bq24188
SLUSC44A – DECEMBER 2014 – REVISED MAY 2015
11.1 Requirements for SYS Output
In order to provide an output voltage on SYS, the bq24188 requires either a power supply between 4.2 V and 6.0
V input on all versions, 4.2 and 14 V on bq24188 with at least 100 mA current rating connected to IN; or, a
single-cell Li-Ion battery with voltage > VBATUVLO connected to BAT. The source current rating needs to be at
least 2.5 A in order for the buck converter of the charger to provide maximum output power to SYS.
11.2 Requirements for Charging
In order for charging to occur the source voltage measured at the IN terminals of the IC, factoring in cable/trace
losses from the source, must be greater than the VINDPM threshold, but less than the maximum values shown
above. The current rating of the source must be higher than the buck converter needs to provide the load on
SYS. For charging at a desired charge current of I_CHRG, V_IN x I_IN x η > V_SYS x (_ISYS+ I_CHRG) where η is the
efficiency estimate from Figure 2 or Figure 3 and VSYS = VBAT when VBAT charges above VMINSYS. The
charger limits I_IN to the current limit setting of that input. With ISYS = 0 A, the charger consumes maximum
power at the end of CC mode, when the voltage at the BAT terminal is near VBATREG but ICHRG has not
started to taper off toward ITERM.
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