AAT1147IJS-0.6-T1 View Datasheet(PDF) - Skyworks Solutions
Part Name
Description
MFG CO.
AAT1147IJS-0.6-T1
Skyworks Solutions
'AAT1147IJS-0.6-T1' PDF : 18 Pages View PDF
DATA SHEET
AAT1147
High Efficiency, Low Noise, Fast Transient 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 = 1.4MHz
TAMB = 85°C
1.8V Output Inductor
μsec
L1 = 3 A
⋅
VO2
=
3
μsec
A
⋅ 1.8V = 5.4μH
(use
4.7μH;
see
Table
1)
For Sumida inductor CDRH3D16, 4.7μH, DCR = 105m.
ΔIL1 =
VO
L1 ⋅ FS
⋅ ⎛⎝1 -
VO ⎞
VIN ⎠
=
1.8V
4.7μH ⋅ 1.4MHz
⋅
⎛⎝1 -
1.8V ⎞
4.2V ⎠
= 156mA
IPKL1
=
IO
+
ΔIL1
2
=
0.4A
+
0.068A
=
0.468A
PL1 = IO2 ⋅ DCR = 0.4A2 ⋅ 105mΩ = 17mW
1.8V Output Capacitor
VDROOP = 0.1V
COUT
=
3 · ΔILOAD
VDROOP · FS
=
3 · 0.3A
0.1V · 1.4MHz
= 6.4μF; use 10µF
IRMS
=
1
2·
· (VO) · (VIN(MAX) - VO)
3 L1 · FS · VIN(MAX)
=1
2·
·
3
1.8V · (4.2V - 1.8V) = 45mArms
4.7μH · 1.4MHz · 4.2V
Pesr = esr · IRMS2 = 5mΩ · (45mA)2 = 10μW
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201986A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
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