COMPONENT POWER DISSIPATION
Operating in discontinuous mode, power loss in
the winding resistance of inductor can be
approximated to
PD L
=
2 TON (Rs) VOUT + VD (POUT)
3 L VOUT
where POUT=VOUT ×IOUT ; Rs=Inductor DC R;
SS6638G
VD = Diode drop.
The power dissipated due to the switch loss is
PDsw = 2 ( ) TON RON VOUT + VD − VIN (POUT)
3 L
VOUT
The power dissipated in the rectifier diode is
PDD = VD (POUT)
VOUT
PHYSICAL DIMENSIONS (unit: mm)
SOT-23-3 (GU)
D
E1
e
e1
A2
b
SYMBOL
A
0.25
A1
E
A2
c
L
b
θ
L1
c
D
E
E1
A
e
A1
e1
L
L1
θ
MIN
MAX
0.95
1.45
0.05
0.15
0.90
1.30
0.30
0.50
0.08
0.22
2.80
3.00
2.60
3.00
1.50
1.70
0.95 BSC
1.90 BSC
0.30
0.60
0.60 REF
0˚
8˚
8/21/2005 Rev.2.3
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