AAT2512
Dual 400mA High Frequency Buck Converter
Design Example
Specifications
VO1 = 2.5V @ 400mA (adjustable using 0.6V version), pulsed load ΔILOAD = 300mA
VO2 = 1.8V @ 400mA (adjustable using 0.6V version), pulsed load ΔILOAD = 300mA
VIN = 2.7V to 4.2V (3.6V nominal)
FS = 1.4 MHz
TAMB = 85°C
2.5V VO1 Output Inductor
μsec
A
μsec
A
(see Table 1)
L1 = 3
⋅ VO1 = 3
⋅ 2.5V = 7.5μH
For Sumida inductor CDRH3D16, 10µH, DCR = 210mΩ.
⎛
⎞
2.5V
⎠
4.2V
VO
L1 ⋅ F
VO1
2.5
V
⎛
⎞
ΔI1 =
⋅ 1 -
⎝
=
⋅ 1 -
= 72.3mA
⎝
VIN
10μH ⋅ 1.4MHz
⎠
ΔI1
2
IPK1 = IO1
+
= 0.4A + 0.036A = 0.44A
PL1 = IO12 ⋅ DCR = 0.4A2 ⋅ 210mΩ = 34mW
1.8V VO2 Output Inductor
μsec
A
μsec
A
(see Table 1)
⋅ 1.8V = 5.4μH
L2 = 3
⋅ VO2 = 3
For Sumida inductor CDRH3D16, 4.7µH, DCR = 105mΩ.
⎛
⎞
1.8V
⎠
4.2V
VO2
L ⋅ F
VO2
VIN
1.8
V
⎛
⎞
⎠
ΔI2 =
⋅ 1 -
⎝
=
⋅ 1 -
= 156mA
⎝
4.7μH ⋅ 1.4MHz
ΔI2
2
IPK2 = IO2
+
= 0.4A + 0.078A = 0.48A
PL2 = IO22 ⋅ DCR = 0.4A2 ⋅ 105mΩ = 17mW
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2512.2006.06.1.4
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
