MB39A132QN-G-ERE1 Datasheet, PDF (45/56 Pages) Fujitsu Component Limited. – ASSP For Power Management Applications (Rechargeable Battery) Synchronous Rectification DC/DC Converter IC for Charging Li-ion Battery

MB39A132
• Allowable loss, and thermal design
In general, the allowable loss and thermal design of this IC can be ignored because this IC is highly effective.
However, when this IC is used with high power supply voltage, high switching frequency, high load, or high
temperature, it is necessary to take account of the allowable loss and thermal design while using this IC.
The IC internal loss (PIC) can be found by the following formula.
PIC = VCC × (ICC + Qg × fOSC )
PIC : IC internal loss [W]
VCC : Power supply voltage (VIN) [V]
ICC : Power supply current [A] (3.6 mA Max)
Qg : Total charge of all switching FET [C] (Total charge at Vgs = 5 V)
fOSC : Switching frequency [Hz]
The junction temperature (Tj) can be found by the following formula.
Tj = Ta + θja × PIC
Tj : Junction temperature [ °C]
Ta : Ambient temperature [ °C]
θja : QFN-32 package heat resistance (22.7 °C/W)
PIC : IC internal loss [W]
DS04–27265–3E
45