AAT1150(2006) Ver la hoja de datos (PDF) - Advanced Analogic Technologies
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AAT1150 Datasheet PDF : 17 Pages
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AAT1150
1MHz 1A Step-Down DC/DC Converter
Design Example
Specifications
IOUT = 1.0A
IRIPPLE = 30% of Full Load at Max VIN
VOUT = 1.5V
VIN = 2.7V to 4.2V (3.6V nominal)
Fs = 830kHz
Maximum Input Capacitor Ripple
IRMS = IO ⋅
VO
VIN
⋅ ⎛⎝1-
VO ⎞
VIN⎠
=
IO
2
= 0.5ARMS, VIN = 2 ⋅ VO
P = ESRCOUT ⋅ IRMS2 = 5mΩ ⋅ 0.52 A = 1.25mW
Inductor Selection
L
=
IO
VOUT
⋅ k ⋅ FS
⋅
⎛⎝1
-
VOUT⎞
VIN ⎠
=
1.0A
⋅
1.5V
0.3 ⋅ 830kHz
⋅ ⎛⎝1 -
1.5V⎞
4.2V⎠
=
3.9μH
Select Sumida inductor CDRH5D18, 4.1μH, 57mΩ, 2.0mm height.
ΔI =
VO
L ⋅ FS
⋅ ⎛⎝1 -
VO ⎞
VIN ⎠
=
1.5V
4.1μH ⋅ 830kHz
⋅
⎛
⎝1-
1.5V ⎞
4.2V⎠
= 280mA
IPK
=
IOUT
+
ΔI
2
=
1.0A
+
0.14A
=
1.14A
P = IO2 ⋅ DCR = 57mW
Output Capacitor Dissipation
IRMS
=
1
2⋅
⋅
3
VOUT ⋅ (VIN - VOUT) =
L ⋅ FS ⋅ VIN
1
2⋅
⋅ 1.5V ⋅ (4.2V - 1.5V)
3 4.1μH ⋅ 830kHz ⋅ 4.2V
= 82mARMS
PESR = ESRCOUT ⋅ IRMS2 = 5mΩ ⋅ 0.0822A = 33μW
14
1150.2006.09.1.5
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