AAT2500 Analogic Corporation, AAT2500 Datasheet - Page 20

• Manufacturer Part Number: AAT2500
• Manufacturer: Analogic Corporation

Step-Down Converter Design Example
Specifications
V
V
V
F
T
1.8V Buck Output Inductor
For Sumida inductor CDRH3D16, 4.7µH, DCR = 105mΩ.
1.8V Output Capacitor
V
L1 = 3
∆I
C
I
20
P
P
I
RMS
PKL1
S
AMB
OBUCK
OLDO
IN
DROOP
L1
OUT
esr
L1
= I
= esr · I
=
=
= I
=
OBUCK
V
µsec
2
L1 ⋅ F
V
OBUCK
= 1.8V @ 400mA (adjustable using 0.6V version), Pulsed Load ∆I
= 3.3V @ 300mA
= 2.7V to 4.2V (3.6V nominal)
= 1.0MHz
= 85°C
= 0.2V
3 · ∆I
OBUCK
·
A
DROOP
1
3
2
RMS
⋅ DCR = 0.4A
·
⋅ V
+
LOAD
⋅ 1 -
(V
· F
2
∆I
⎛
⎝
O2
= 5mΩ · (63mA)
OBUCK
2
S
L1
= 3
=
= 0.4A + 0.11A = 0.51A
V
L1 · F · V
V
) · (V
OBUCK
0.2V · 1MHz
µsec
IN
3 · 0.3A
A
⎞
⎠
IN(MAX)
2
=
⋅ 1.8V = 5.4µH
⋅ 105mΩ = 17mW
4.7µH ⋅ 1.0MHz
IN(MAX)
- V
2
= 20µW
= 4.5µF
1.8 V
OBUCK
)
=
2
·
1
1MHz Step-Down Converter/LDO Regulator
⋅ 1 -
(see Table 1)
3
⎛
⎝
·
4.7µH · 1.0MHz · 4.2V
1.8V
1.8V · (4.2V - 1.8V)
4.2V
⎞
⎠
= 218mA
= 63mArms
LOAD
= 300mA
AAT2500
2500.2005.08.1.9