AAT1152 View Datasheet(PDF) - Advanced Analogic Technologies
Part Name
Description
MFG CO.
'AAT1152' PDF : 17 Pages View PDF
AAT1152
850kHz 1A Buck DC/DC Converter
Design Example:
Specifications
IOUT
IRIPPLE
VOUT
VIN
Fs
1A
30% of full load at max VIN
1.5V
2.7V to 4.2V (3.6V nominal)
830kHz
Maximum Input Capacitor Ripple:
IRMS = IO ⋅
VO
VIN
⋅ ⎝⎛1-
VO ⎞
VIN⎠
=
IO
2
=
0.5ARMS,
VIN
=
2
⋅
VO
P = ESRCOUT ⋅ IRMS2 = 5mΩ ⋅ 0.52A = 1.25mW
Inductor Selection:
L
=
IO
VOUT
⋅ k ⋅ FS
⋅
⎛⎝1
-
VOUT⎞
VIN ⎠
=
1A
⋅
1.5V
0.3 ⋅ 830kHz
⋅
⎛⎝1
-14..52VV⎞⎠
= 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
=
1A
+
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
1152.2006.09.1.7
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