AAT2511 Datasheet, PDF (14/20 Pages) Advanced Analogic Technologies – Dual 600mA, 1MHz Step-Down DC/DC Converter

AAT2511
Dual 600mA, 1MHz Step-Down DC/DC Converter
Design Example
Specifications
V_O1 = 2.5V @ 600mA (adjustable using 0.6V version), pulsed load ∆I_LOAD = 300mA
V_O2 = 1.8V @ 600mA (adjustable using 0.6V version), pulsed load ∆I_LOAD = 300mA
V_IN = 2.7V to 4.2V (3.6V nominal)
F_S = 1.0 MHz
T_AMB = 85°C
2.5V V_O1 Output Inductor
µsec
µsec
L1 = 3 _A ⋅ V_O1 = 3 _A ⋅ 2.5V = 7.5µH
(see Table 1)
For Sumida inductor CDRH3D16, 10µH, DCR = 210mΩ.
∆I1 =
V_O
L1 ⋅ F
⋅
⎛⎝₁
-
V_O1⎞
V_IN ⎠
=
2.5V
10µH ⋅ 1.0MHz
⋅
⎛⎝₁
-
2.5V⎞
4.2V⎠
= 100mA
I_PK1
=
I_O1
+
∆I1
2
=
0.6A
+
0.05A
=
0.65A
P_L1 = I_O12 ⋅ DCR = (0.4A)² ⋅ 210mΩ = 76mW
1.8V V_O2 Output Inductor
µsec
µsec
L2 = 3 _A ⋅ V_O2 = 3 _A ⋅ 1.8V = 5.4µH
(see Table 1)
For Sumida inductor CDRH3D16, 4.7µH, DCR = 105mΩ.
∆I2 =
V_O2
L⋅F
⋅
⎛⎝₁
-
V_O2 ⎞
V_IN ⎠
=
1.8V
4.7µH ⋅ 1.0MHz
⋅
⎛⎝₁
-
1.8V ⎞
4.2V⎠
= 218mA
I_PK2
=
I_O2
+
∆I2
2
=
0.6A
+
0.11A
=
0.71A
P_L2 = I_O22 ⋅ DCR = (0.6A)² ⋅ 105mΩ = 38mW
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2511.2006.02.1.2