AAT2510
Dual 400mA, 1MHz Step-Down DC-DC Converter
2.5V Output Capacitor
3 · ∆ILOAD
VDROOP · FS
3 · 0.3A
0.2V · 1MHz
COUT
=
=
= 4.5µF
(VOUT) · (VIN(MAX) - VOUT
)
1
2.5V · (4.2V - 2.5V)
1
·
= 29mArms
IRMS(MAX)
=
·
=
10µH · 1MHz · 4.2V
L · F · VIN(MAX)
2· 3
2· 3
Pesr = esr · IRMS2 = 5mΩ · (29mA)2 = 4.2µW
1.8V Output Capacitor
3 · ∆ILOAD
VDROOP · FS
3 · 0.3A
COUT
=
=
= 4.5µF
0.2V · 1MHz
(VOUT) · (VIN(MAX) - VOUT
)
1
1.8V · (4.2V - 1.8V)
1
·
= 63mArms
IRMS(MAX)
=
·
=
4.7µH · 1.0MHz · 4.2V
L · F · VIN(MAX)
2· 3
2· 3
Pesr = esr · IRMS2 = 5mΩ · (63mA)2 = 20µW
Input Capacitor
Input Ripple VPP = 25mV.
1
1
CIN =
=
= 9.5µF
⎛
VPP
⎝IO1 + IO2
⎞
⎠
⎛ 25mV
⎝ 0.8A
⎞
⎠
- ESR • 4 • FS
- 5mΩ • 4 • 1MHz
IO1 + IO2
IRMS(MAX)
=
= 0.4Arms
2
P = esr · IRMS2 = 5mΩ · (0.4A)2 = 0.8mW
2510.2005.08.1.5
15
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
