PRODUCT DATASHEET
AAT2113A
TM
SwitchReg
3MHz, FastTransient 1.5A Step-Down Converter in 2mm x 2mm Package
AAT2113A Design Example
Specifications
VOUT = 1.2V @ 1.5A, Pulsed Load ΔILOAD = 1.5A
VIN = 3.3V
FS = 3MHz
TAMB = 85°C in 8-pin 2x2mm DFN low profile package
Output Inductor
For Murata, 0.47μH LQM2HPNNR47MG0 shielded chip inductor has a 40mΩ DCR.
VO
L1 · FS
VO
VIN
1.2
V
1.2V
3.3V
ΔI =
· 1 -
=
· 1 -
= 542mA
0.47μH · 3MHz
ΔI
2
IPK = IOUT
+
= 1.5A + 0.271A = 1.8A
PL1 = IOUT2 · DCR = 1.5A2 · 40mΩ = 90mW
Output Capacitor
For VDROOP = 0.12V (10% Output Voltage)
3 · ΔILOAD
VDROOP · FS
3 · 1.5A
0.12V · 3MHz
COUT
=
=
= 12.5μF; use 10μF
For VDROOP = 0.06V (5% Output Voltage)
3 · ΔILOAD
VDROOP · FS 0.06V · 3MHz
3 · 1.5A
COUT
=
=
= 25μF; use 22μF
VOUT · (VIN(MAX) - VOUT
)
1
1.2V · (5V - 1.2V)
1.5μH · 3MHz · 5V
1
·
= 58.5mArms
IRMS(MAX)
=
·
=
L · FS · VIN(MAX)
2· 3
2· 3
PRMS = ESR · IRMS2 = 5mΩ · (58.5mA)2 = 17μW
w w w . a n a l o g i c t e c h . c o m
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2113A.2009.06.1.1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
