TLE8386-2EL Datasheet, PDF (22/32 Pages) Infineon Technologies AG – Basic Smart Boost Controller

TLE8386-2EL
10.1.2 Component Selection:
Application Information
Power MOSFET selection:
The important parameters for the choice of the power MOSFET are:
• Drain-source voltage rating V_DS: The power MOSFET will see the full output voltage V_BO plus the output diode
(D_BOOST) forward voltage. During its off-time additional ringing across drain-to-source will occur.
• On-resistance R_DSON for efficiency reasons and power dissipation
• Maximum drain current I_DMAX
• Gate-to-source charge and gate-to-drain charge
• Thermal resistance
It is recommended to choose a power MOSFET with a drain-source voltage rating V_DS of at least 10 V higher than
the output voltage V_BO.
The power dissipation P_LOSSFET in the power MOSFET can be calculated using the following formula:
• C_RSS = reverse transfer capacitance, please refer to power MOSFET data sheet
• I_BOOSTMAX = maximum average current through the boost inductor L_BOOST.
P_LOSSFET
=
I_BOOSTMAX2
×
R_DSON
+
2
×
V_{B2 O}
×
I_BOOSTMAX
×
C_RSS
×
f---_{F--R----E---Q-}
1A
The first term in the equation above gives the conduction losses in the power MOSFET, the second term the
switching losses. To optimize the efficiency, R_DSON and C_RSS should be minimized.
Data Sheet
20
Rev. 1.0, 2010-10-25