MB3882 Datasheet, PDF (22/30 Pages) Fujitsu Component Limited. – 2-channel DC/DC Converter IC with Synchronous Rectifier

MB3882
s PRECAUTIONS RELATED TO INTERNAL IC POWER CONSUMPTION
The internal power dissipation in the IC is greatly affected by the oscillator frequency and the FET total gate
charge. When using the MB 3882 in an application, caution must be taken in relation to internal IC power
consumption.
As shown below, IB (average current) can be determined from the total gate charge Qg1, Qg2, charged from the
gate capacitance (Ciss1, Ciss2, Crss1, Crss2) of the external FET Q1, Q2, by the following formula.
Per individual channel :
IB (A) = I1 + I2
=: Ibias1 ×
T1 Qg1
T2 Qg2
T ⁺ T ^{+ Ibias2 ×} T ⁺ T
(Ibias1 = Ibias2 =: 2 mA)
Because IC current consumption other than IB is 11 mA, power consumption can be determined from the following
formula.
Power consumption : Pc
Pc (W) = 0.011 × VCC + 2 × VCC × IB − VB × IB
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