APPLICATION NOTE AN50
7
MOSFET Selection
This application requires N-channel Logic Level Enhance-
ment Mode Field Effect Transistors. Desired characteristics
are as follows:
• Low Static Drain-Source On-Resistance,
RDS,ON < 37 mΩ (lower is better)
• Low gate drive voltage, VGS ≤ 4.5V
• Power package with low Thermal Resistance
• Drain current rating of 20A minimum
• Drain-Source voltage > 15V.
The on-resistance (RDS,ON) is the primary parameter for
MOSFET selection. It determines the power dissipation
within the MOSFET and, therefore, significantly affects the
efficiency of the DC-DC converter. Table 5 is a selection
table for MOSFETs.
Note:
1. RDS,ON values at Tj = 125°C for most devices were extrapolated from the typical operating curves supplied by the
manufacturers and are approximations only.
Table 3. MOSFET Selection Table Manufacturer & Model # Conditions1
RDS, ON (mΩ)
Package Thermal
ResistanceTyp. Max.
Fuji
2SK1388 VGS = 4V, ID = 17.5A TJ = 25°C 25 37 TO-220 ΦJA = 75
TJ = 125°C 37 —
Siliconix
SI4410DY VGS = 4.5V, ID = 5A TJ = 25°C 16.5 20 SO-8
(SMD) ΦJA = 50
TJ = 125°C 28 34
National Semiconductor
NDP706AL VGS = 5V, ID = 40A TJ = 25°C 13 15 TO-220 ΦJA = 62.5
ΦJC = 1.5
NDP706AEL TJ = 125°C 20 24
National Semiconductor VGS = 4.5V, ID = 10A TJ = 25°C 31 40 TO-220 ΦJA = 62.5
NDP603AL TJ = 125°C 42 54 ΦJC= 2.5
National Semiconductor VGS = 5V, ID = 24A TJ = 25°C 22 25 TO-220 ΦJA= 62.5
NDP606AL TJ = 125°C 33 40 ΦJC = 1.5
Motorola VGS = 5V, ID = 37.5A TJ = 25°C 6 9 TO-263 ΦJA = 62.5
MTB75N03HDL TJ = 125°C 9.3 14 (D2 PAK) ΦJC = 1.0
Int. Rectifier VGS = 5V, ID = 31A TJ = 25°C — 28 TO-220 ΦJA = 62.5
IRLZ44 TJ = 125°C — 46 ΦJC = 1.0
Int. Rectifier VGS = 4.5V, ID = 28A TJ = 25°C — 19 TO-220 ΦJA = 62.5
IRL3103S TJ = 125°C — 31 ΦJC = 1.0
Intl Rectifier VGS = 4.5V,
ID = 3.7A TA = 25°C 18 SO-8 ΦJA = 50
IRF7413 SMD