AAT1143IJS-0.6-T1 View Datasheet(PDF) - Advanced Analogic Technologies
Part Name
Description
MFG CO.
'AAT1143IJS-0.6-T1' PDF : 20 Pages View PDF
AAT1143
1MHz 400mA Step-Down Converter
Step-Down Converter Design Example
Specifications
VO = 1.8V @ 400mA (adjustable using 0.6V version), Pulsed Load ΔILOAD = 300mA
VIN = 2.7V to 4.2V (3.6V nominal)
FS
= 1.0MHz
TAMB = 85°C
1.8V Output Inductor
μsec
μsec
L1 = 3 A ⋅ VO2 = 3 A ⋅ 1.8V = 5.4μH (see Table 1)
For Sumida inductor CDRH3D16, 4.7μH, DCR = 105mΩ.
ΔIL1 =
VO
L1 ⋅ FS
⋅
⎛⎝1 -
VO ⎞
VIN ⎠
=
1.8V
4.7μH ⋅ 1.0MHz
⋅
1
-
⎛ 1.8V⎞
⎝ 4.2V⎠
=
218mA
IPKL1
=
IO
+
ΔIL1
2
=
0.4A
+
0.11A
=
0.51A
PL1 = IO2 ⋅ DCR = 0.4A2 ⋅ 105mΩ = 17mW
1.8V Output Capacitor
VDROOP = 0.2V
COUT
=
3 · ΔILOAD
VDROOP · FS
=
3 · 0.3A
0.2V · 1MHz
= 4.5μF
IRMS
=
1 · (VO) · (VIN(MAX) - VO) = 1 ·
2· 3 L1 · FS · VIN(MAX) 2· 3
1.8V · (4.2V - 1.8V) = 63mArms
4.7μH · 1.0MHz · 4.2V
Pesr = esr · IRMS2 = 5mΩ · (63mA)2 = 20μW
1143.2006.07.1.10
15
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