AAT1275
Boost Converter with USB Power Switch
VIN(MIN) · DMAX
L · FS
IPP
=
IO
1 - D
IP =
IPP
2
IPK = IP +
IV = IP - IPP
IV = IP - IPP = 0.9A - 0.7A = 0.20A
2
IPK2 + IPK · IV + IV
0.9A2 + 0.9A · 0.2A + 0.2A2
IRMS
=
=
= 0.59A
3
3
For the Sumida CDRH2D14-2R2 inductor, ISAT = 1.0A, IDC(MAX) = 1.6A and DCR = 94mΩ.
PLOSS(INDUCTOR) = I2
·
DCR = (590mA)2 · 94mΩ = 32mW
RMS
5V Output Capacitor
ΔVOUT = 0.05V
IOUT · DMAX
FS · ΔVOUT
0.3A · 0.46
800kHz · 0.05V
COUT(MIN)
=
=
= 3.0µF; use 4.7µF 10V MLC
16
1275.2007.01.1.3