AAT1120IES-0.6-T1 View Datasheet(PDF) - Skyworks Solutions
Part Name
Description
MFG CO.
'AAT1120IES-0.6-T1' PDF : 19 Pages View PDF
Step-Down Converter Design Example
Specifications
VO = 1.8V @ 250mA, Pulsed Load ILOAD = 200mA
VIN = 2.7V to 4.2V (3.6V nominal)
FS = 1.5MHz
TAMB = 85°C
1.8V Output Inductor
µsec
µsec
L1 = 1.67 A ⋅ VO2 = 1.67 A ⋅ 1.8V = 3µH (use 3.0μH; see Table 1)
For Sumida inductor CDRH2D09-3R0, 3.0μH, DCR = 150m.
ΔIL1 =
VO
L1 ⋅ FS
⋅
⎛⎝1
-
VO⎞
VIN⎠
=
1.8V
3.0µH ⋅ 1.5MHz
⋅
⎛
⎝
1
-
1.8V⎞
4.2V⎠
= 228mA
IPKL1
=
IO
+
ΔIL1
2
=
250mA
+
114mA
=
364mA
PL1 = IO2 ⋅ DCR = 250mA2 ⋅ 150mΩ = 9.375mW
1.8V Output Capacitor
VDROOP = 0.1V
COUT
=
3 · ΔILOAD
VDROOP · FS
=
3 · 0.2A
0.1V · 1.5MHz
= 4µF (use 4.7µF)
IRMS
=
1
2·
· (VO) · (VIN(MAX) - VO)
3
L1 · FS · VIN(MAX)
=1
2·
·
3
1.8V · (4.2V - 1.8V) = 66mArms
3.0µH · 1.5MHz · 4.2V
Pesr = esr · IRMS2 = 5mΩ · (66mA)2 = 21.8µW
DATA SHEET
AAT1120
500mA Step-Down Converter
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201973B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 15, 2013
15
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