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AAT2506 Datasheet, PDF (20/26 Pages) Advanced Analogic Technologies – 1MHz Step-Down Converter/LDO Regulator | |||
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AAT2506
1MHz Step-Down Converter/LDO Regulator
Step-Down Converter Design Example
Specifications
VOBUCK = 1.8V @ 400mA (adjustable using 0.6V version), Pulsed Load âILOAD = 300mA
VOLDO = 3.3V @ 300mA
VIN = 2.7V to 4.2V (3.6V nominal)
FS
= 1.0MHz
TAMB = 85°C
1.8V Buck Output Inductor
µsec
µsec
L1 = 3 A â
VO2 = 3 A â
1.8V = 5.4µH
(see Table 1)
For Sumida inductor CDRH3D16, 4.7µH, DCR = 105mâ¦.
âIL1 =
VOBUCK
L1 â
F
â
ââ1 -
VOBUCKâ
VIN â
=
1.8V
4.7µH â
1.0MHz
â
ââ1
-
1.8V â
4.2Vâ
=
218mA
IPKL1
=
IOBUCK
+
âIL1
2
=
0.4A
+
0.11A
=
0.51A
PL1
=
I2
OBUCK
â
DCR
=
0.4A2
â
105mâ¦
=
17mW
1.8V Output Capacitor
VDROOP = 0.05V
COUT
=
3 · âILOAD
VDROOP · FS
=
3 · 0.3A
0.05V · 1MHz
= 18µF
IRMS
=
1 · (VOBUCK) · (VIN(MAX) - VOBUCK) = 1 ·
2· 3
L1 · F · VIN(MAX)
2· 3
1.8V · (4.2V - 1.8V) = 63mArms
4.7µH · 1.0MHz · 4.2V
Pesr = esr · IRMS2 = 5m⦠· (63mA)2 = 20µW
20
2506.2005.12.1.0
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