AAT2113B Datasheet, PDF (19/22 Pages) Skyworks Solutions Inc. – 3.3MHz, Fast Transient 1.5A Step-Down Converter in an 2mm x 2mm Package

DATA SHEET
AAT2113B
3.3MHz, Fast Transient 1.5A Step-Down Converter in an 2mm x 2mm Package
AAT2113B Design Example
Specifications
V_OUT = 1.2V @ 1.5A, Pulsed Load I_LOAD = 1.5A
V_IN = 3.3V
F_S = 3.3MHz
T_AMB = 85°C in 8-pin 2x2mm DFN low profile package
Output Inductor
For Murata, 0.47μH LQM2HPNNR47MG0 shielded chip inductor has a 40mΩ DCR.
ΔI
=
V_O
L1 · F_S
·
1-
V_O
V_IN
=
1.2V
0.47μH · 3.3MHz
·
1
-
1.2V
3.3V
= 0.492mA
I_PK
=
I_OUT
+
ΔI
2
=
1.5A
+
0.271A
=
1.75A
P_L1 = I_OUT2 · DCR = 1.5A² · 40mΩ = 90mW
Output Capacitor
For V_DROOP = 0.12V (10% Output Voltage)
C_OUT
=
3 · ΔI_LOAD
V_DROOP · F_S
=
3 · 1.5A _{= 11.4μF; use 10μF}
0.12V · 3.3MHz
For V_DROOP = 0.06V (5% Output Voltage)
C_OUT
=
3 · ΔI_LOAD
V_DROOP · F_S
=
3 · 1.5A _{= 22.7μF; use 22μF}
0.06V · 3.3MHz
I = _RMS(MAX)
1 _· V_OUT · (V_IN(MAX) - V_OUT) ₌ 1 _·
2· 3
L · F_S · V_IN(MAX)
2· 3
1.2V ·
0.47μH
(3.3V - 1.2V)
· 3.3MHz · 3.3V
=
142mA_rms
P_RMS = ESR · I_RMS2 = 5mΩ · (142mA)² = 0.1mW
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
202003A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 24, 2012
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