MB39A132QN-G-ERE1 Fujitsu Semiconductor America Inc, MB39A132QN-G-ERE1 Datasheet - Page 41

• 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

DS04–27265–3E
• Bootstrap diode selection
Select a Schottky barrier diode (SBD) that has a small forward voltage drop.
The current to drive the gate of High-side FET flows to the SBD of the bootstrap circuit. The average current
can be found by the following formula. Select a bootstrap diode that keep the average current below the
current rating.
The rating of the bootstrap diode can be found by the following formula.
• Bootstrap capacitor selection
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 10 times Qg of the high-side FET as the bootstrap capacitor.
The rating of bootstrap capacitor can be found by the following formula.
C
I
I
Qg
f
V
V
V
C
Qg
V
V
V
V
BOOT
D
D
OSC
R_BOOT
R_BOOT
IN
B
CBOOT
CBOOT
IN
BOOT
≥ Qg × f
≥ 10 ×
: Forward current [A]
: FET total gate electric charge of high-side [C]
: Oscillation frequency [Hz]
: Bootstrap capacitance [F]
: Withstand voltage FET gate charge [C]
: VB voltage [V]
> V
: Rating of bootstrap capacitor [V]
: Switching power supply voltage [V]
> V
: Bootstrap diode DC reverse voltage [V]
: Switching power supply voltage [V]
OSC
IN
IN
Qg
V
B
MB39A132
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