MB39C011APFT-G-BND-ERE1 Datasheet, PDF (40/53 Pages) Cypress Semiconductor – 2 ch DC/DC Converter IC with Synchronous Rectification

MB39C011A
19.6 VB pin capacitor
Although the VB pin capacitor typically has a capacitance of 1 F, this needs to be adjusted if the SW FET being used has a large Qg.
The following formula provides a guide to the lower limit of the VB pin capacitor. If this lower limit exceeds 1 F, use the formula
as a guide to set the capacitance.
CVBmin ≥ 0.1 QgLoSideFET
CVBmin
: Lower limit of VB pin capacitor [F]
QgLoSideFET : Sum total electric charge of CH1 and CH2 Low side FETs [nC]
19.7 VH pin capacitor
The VH pin capacitor typically has a capacitance of 1 F (when the VB pin capacitor  1 F). However, this needs to be adjusted,
if the VB pin capacitor exceeds 1 F or if the SW FET being used has a large Qg.
The following formula provides a guide to the lower limit of the VH pin capacitor. If this lower limit exceeds 1 F, use the formula
as a guide to set the capacitance.
Large one either of
CVHmin ≥ 0.01QgHiSideFET or CVHmin ≥ CVB
CVHmin
QgHiSideFET
CVB
: Lower limit of VH pin capacitor [F]
: Sum total electric charge of CH1 and CH2 high side FETs [nC]
: Capacitance of VB pin capacitor [F]
Document Number: 002-08369 Rev. *A
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