BQ76200: How to estimate Charge-pump cap?

Kotaro Yamashita

Part Number: BQ76200

Hi Team,

How to estimate charge pump capacitance(Cvddcp)? The D/S mentioned user should connect 470nF at least. However, I guess it is depend on Gate capacitance of MOSFETs. Is my understanding correct?

Regards,

Kotaro Yamashita

over 5 years ago

0 WM5295 over 5 years ago

TI__Guru 54715 points

Hi Kotaro,

Please see the data sheet section 8.1.1.3, http://www.ti.com/document-viewer/BQ76200/datasheet/scalable-vddcp-capacitor-to-support-multiple-fets-in-parallel-slusc161521#SLUSC161521 It indicates to keep the ratio of 470 nF/ 20 nF for CVDDCP/gate capacitance or 23.5 x the gate capacitance. The 470 nF is the minimum recommended.

See http://www.ti.com/lit/pdf/slva729 for examples driving multiple FETs and http://www.ti.com/lit/pdf/slua794 for general considerations. In many systems external gate resistance is needed.

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BQ76200: How to estimate Charge-pump cap?