AAT1143IJS-1.6-T1 View Datasheet(PDF) - Analog Technology Inc
Part Name
Description
MFG CO.
'AAT1143IJS-1.6-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 ∆ILOAD = 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.
∆IL1 =
VO
L1 ⋅ F
⋅
⎛⎝1
-
VO ⎞
VIN ⎠
=
1.8V
4.7µH ⋅ 1.0MHz
⋅
1
-
⎛
⎝
1.8V⎞
4.2V⎠
=
218mA
IPKL1
=
IO
+
∆IL1
2
=
0.4A
+
0.11A
=
0.51A
PL1 = IO2 ⋅ DCR = 0.4A2 ⋅ 105mΩ = 17mW
1.8V Output Capacitor
VDROOP = 0.2V
COUT
=
3 · ∆ILOAD
VDROOP · FS
=
3 · 0.3A
0.2V · 1MHz
=
4.5µF
IRMS
=
1 · (VO) · (VIN(MAX) - VO)
2· 3
L1 · F · VIN(MAX)
=1
2·
·
3
1.8V · (4.2V - 1.8V) = 63mArms
4.7µH · 1.0MHz · 4.2V
Pesr = esr · IRMS2 = 5mΩ · (63mA)2 = 20µW
1143.2005.09.1.7
15
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