SLUSFR7 August 2025 BQ24810
PRODUCTION DATA
CSYS capacitance combines with CIN to provide output capacitance when BQ24810 is operating in battery only boost mode and provides bulk capacitance in all modes to support fast load transients on SYS. The distinction between CIN and CSYS is that CIN is ceramic capacitor only and must be placed very close to the high side switching MOSFET Q4. CSYS may be a mixture of ceramic and tantalum capacitors and does not have as tight of a placement requirement.
If battery only boost mode is supported, the sum of ( CSYS + CIN) is chosen according to the internal compensation requirement of the Section 7.2.1.2.8 section.
Ceramic capacitors show a dc-bias effect. This effect reduces the effective capacitance when a dc-bias voltage is applied across a ceramic capacitor, as on the input capacitor of a charger. The effect may lead to a significant capacitance drop, especially for high input voltages and small capacitor packages. See the manufacturer's data sheet about the performance with a dc bias voltage applied. It may be necessary to choose a higher voltage rating or nominal capacitance value in order to get the required value at the operating point.