AAT1275
Boost Converter with USB Power Switch
AAT1275 Losses
2
(IPK2 + IPK · IV + IV ) · DMAX
(0.9A2 + 0.9A · 0.2A + 0.2A2) · 0.46
= 0.4A
IRMS(ON)
=
=
3
3
2
(IPK2 + IPK · IV + IV ) · (1 - DMAX
)
(0.9A2 + 0.9A · 0.2A + 0.2A2) · (1 - 0.46)
IRMS(OFF)
=
=
= 0.43A
3
3
PTOTAL = IRMS(ON)2 · (RDS(ON)IN
= 0.4A2 · (0.25Ω
+
RDS(ON)N) + IRMS(OFF)2 · (RDS(ON)IN
+
RDS(ON)P + RDS(ON))
+
0.3Ω) + 0.422 · (0.25Ω
+
0.3Ω
+
0.2Ω
) = 0.22W
110°C
W
TJ(MAX)
=
P
TOTAL · θJA
+
TAMB
=
0.22W
·
+ 85°C = 109°C
1275.2007.01.1.3
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