PRODUCT DATASHEET
AAT2784
SystemPowerTM
3-Channel Step-Down DC/DC Converter
Design Example
Specifications
VO3
VO1
VO2
VIN
FS
1.2V @ 1.5A (adjustable using 0.6V version), pulsed load ΔILOAD = 1.5A
3.3V @ 300mA (adjustable using 0.6V version), pulsed load ΔILOAD = 300mA
3.3V @ 300mA (adjustable using 0.6V version), pulsed load ΔILOAD = 300mA
2.7V to 4.2V (3.6V nominal)
1.8 MHz
85°C
TAMB
Channel 3 Output Inductor
0.75 VO
m
0.75 1.2V
A
0.75
µs
; use 1.5μH. (see Table 4).
= 1.2µH
L =
=
Select Murata LQH32PN1R5NN0L 1.5ꢀH 1.75A DC current rating DCR = 68mΩ.
VO3
L F
VO3
VIN
1.5
V
1.5V
4.2V
ΔI3 =
1 -
=
1 -
= 357mA
1.5µH 1.8MHz
IPK3 = 1.5A + 0.36A = 1.86A
2
PL3 = IO3 DCR = 1.5A2 68mΩ = 153mW
Channels 1 and 2 Output Inductors
0.75 VO
m
0.75 3.3V
A
0.6
µs
L1 = L2 =
=
= 4.1µH
; use 4.7μH. (see Table 4)
Select Sumida CDRH2D11 4.7ꢀH 0.88A DC current rating DCR = 170mΩ.
VO1
L F
VO1
VIN
3.3
V
3.3V
4.2V
ΔI1 = ΔI2 =
1 -
=
1 -
= 84mA
4.7µH 1.8MHz
IPK1 = IPK2 = 0.3A + 0.084A = 0.384A
2
PL1 = PL2 = IO1 DCR = 0.32 170mΩ = 15.3mW
w w w . a n a l o g i c t e c h . c o m
2784.2007.11.1.1
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