BQ24705 Datasheet, PDF (22/30 Pages) Texas Instruments – Host-Controlled Multi-Chemistry Battery Charger With Low Input Power Detect

bq24705
SLUS779 – DECEMBER 2007
www.ti.com
Figure 31 shows the measured input voltages and currents with different input capacitances. The voltage spike
drops by about 5 V after increasing Ci from 20 µF to 40 µF. The input voltage spike has been dramatically
damped by using a 47 F electrolytic capacitor.
Figure 31. Adapter DC Side Hot Plug-In With Various Input Capacitances
Since the input voltage to the IC is PVCC which is 0.7 V (diode voltage drop) lower than Vc during the adapter
insertion, a 40-µF input capacitance is normally adequate to keep the PVCC voltage well below the maximum
voltage rating under normal conditions. In case of a higher input stray inductance, the input capacitance may be
increased accordingly. An electrolytic capacitor will help reduce the input voltage spike due to its high ESR.
22
Submit Documentation Feedback
Product Folder Link(s) :bq24705
Copyright © 2007, Texas Instruments Incorporated