MB39A132QN-G-ERE1 Fujitsu Semiconductor America Inc, MB39A132QN-G-ERE1 Datasheet - Page 42

• Manufacturer Part Number: MB39A132QN-G-ERE1
• Description: IC CONV DC-DC LI-ION 32QFN
• Manufacturer: Fujitsu Semiconductor America Inc

Specifications of MB39A132QN-G-ERE1

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Operating Temperature: 25°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 865-1020

MB39A132
42
• VB capacitor
Although the typical capacitance value for a VB capacitor is 1 μF, it has to be adjusted if the switching FET
used has a large Qg. The bootstrap capacitor needs to be sufficiently charged to drive the gate of the high-
side FET. Therefore, select a capacitor that can store charge at least 100 times the total of Qg of the high-
side FET and Qg of the low-side switching FET as the VB capacitor.
The rating of VB capacitor can be found by the formula.
C
C
Qg
VB
V
V
V
VB
CVB
CVB
B
VB
≥ 100 ×
> V
: VB pin capacitance [F]
: Total gate charge of high-side FET and low-side switching FET [C]
: VB voltage [V]
: Withstand voltage of VB capacitor [V]
:VB voltage [V]
B
Qg
V
B
DS04–27265–3E