AAT2513
Dual 600mA Step-Down
Converter with Synchronization
1.8V Output Capacitor
3 · ΔILOAD
VDROOP · FS
3 · 0.3A
0.2V · 1.7MHz
COUT
=
=
= 4.8µF
(VOUT) · (VIN(MAX) - VOUT
)
1
1.8V · (4.2V - 1.8V)
1
·
= 31mArms
IRMS(MAX)
=
·
=
2.2µH · 1.7MHz · 4.2V
L · F · VIN(MAX)
2· 3
2· 3
Pesr = esr · IRMS2 = 5mΩ · (31mA)2 = 4.8µW
2.5V Output Capacitor
3 · ΔILOAD
VDROOP · FS
3 · 0.3A
COUT
=
=
= 4.8µF
0.2V · 1.7MHz
(VOUT) · (VIN(MAX) - VOUT
)
1
2.5V · (4.2V - 2.5V)
1
·
= 67mArms
IRMS(MAX)
=
·
=
3.3µH · 1.7MHz · 4.2V
L · F · VIN(MAX)
2· 3
2· 3
Pesr = esr · IRMS2 = 5mΩ · (67mA)2 = 22µW
Input Capacitor
Input Ripple VPP = 25mV.
1
1
CIN =
=
= 10µF
⎛
⎝
VPP
+
⎞
⎠
⎛
⎝
25mV
1.2A
⎞
· 4
- ESR
·
4
·
FS
- 5mΩ
· 1.7MHz
IO1
IO2
⎠
IO1 + IO2
2
IRMS(MAX)
P = esr
=
·
= 0.6Arms
IRMS2 = 5mΩ
·
(0.6A)2 = 0.8mW
2513.2007.04.1.1
17
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
