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| AAT1276 Datasheet, PDF (16/18 Pages) Advanced Analogic Technologies – Boost Converter with USB Power Switch | |||
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SwitchRegTM
PRODUCT DATASHEET
AAT1276
Boost Converter with USB Power Switch
5V Output Capacitor
ÎVOUT = 0.05V
COUT(MIN) =
IOUT · DMAX
FS · ÎVOUT
=
0.3A · 0.46
800kHz · 0.05V
= 3.0µF; use 4.7µF 10V MLC
AAT1276 Losses
IRMS(ON) =
(IPK2 + IPK · IV + IV2) · DMAX =
3
(0.9A2 + 0.9A · 0.2A + 0.2A2) · 0.46 = 0.4A
3
IRMS(OFF) =
(IPK2 + IPK · IV + IV2) · (1 - DMAX) =
3
(0.9A2 + 0.9A · 0.2A + 0.2A2) · (1 - 0.46) = 0.43A
3
PTOTAL = IRMS(ON)2 · (RDS(ON)IN + RDS(ON)N) + IRMS(OFF)2 · (RDS(ON)IN + RDS(ON)P + RDS(ON))
= 0.4A2 · (0.25Ω + 0.3Ω) + 0.422 · (0.25Ω + 0.3Ω + 0.2Ω) = 0.22W
TJ(MAX)
=
PTOTAL
·
θJA
+
TAMB
=
0.22W
·
110°C
W
+
85°C
=
109°C
16
www.analogictech.com
1276.2007.11.1.1
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