AAT2512 Datasheet, PDF (14/20 Pages) Advanced Analogic Technologies – Dual 400mA High Frequency Buck Converter

AAT2512
Dual 400mA High Frequency Buck Converter
Design Example
Specifications
V_O1 = 2.5V @ 400mA (adjustable using 0.6V version), pulsed load ΔI_LOAD = 300mA
V_O2 = 1.8V @ 400mA (adjustable using 0.6V version), pulsed load ΔI_LOAD = 300mA
V_IN = 2.7V to 4.2V (3.6V nominal)
F_S = 1.4 MHz
T_AMB = 85°C
2.5V V_O1 Output Inductor
L1
=
3
μsec
A
⋅
V_O1
=
3
μsec
A
⋅ 2.5V = 7.5μH
(see Table 1)
For Sumida inductor CDRH3D16, 10µH, DCR = 210mΩ.
ΔI1 =
V_O
L1 ⋅ F
⋅
⎛⎝₁
-
V_O1⎞
V_IN ⎠
=
2.5V
10μH ⋅ 1.4MHz
⋅
⎛⎝₁
-
2.5V⎞
4.2V⎠
= 72.3mA
I_PK1
=
I_O1
+
ΔI1
2
=
0.4A
+
0.036A
=
0.44A
P_L1 = I_O12 ⋅ DCR = 0.4A² ⋅ 210mΩ = 34mW
1.8V V_O2 Output Inductor
L2
=
3
μsec
A
⋅
V_O2
=
3
μsec
A
⋅ 1.8V = 5.4μH
(see Table 1)
For Sumida inductor CDRH3D16, 4.7µH, DCR = 105mΩ.
ΔI2 =
V_O2
L⋅F
⋅
⎛₁
⎝
-
V_O2 ⎞
V_IN ⎠
=
1.8V
4.7μH ⋅ 1.4MHz
⋅
⎛⎝₁
-
1.8V ⎞
4.2V⎠
= 156mA
I_PK2
=
I_O2
+
ΔI2
2
=
0.4A
+
0.078A
=
0.48A
P_L2 = I_O22 ⋅ DCR = 0.4A² ⋅ 105mΩ = 17mW
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