AAT1143IJS-1.8-T1 AnalogicTech, AAT1143IJS-1.8-T1 Datasheet - Page 15

• Manufacturer Part Number: AAT1143IJS-1.8-T1
• Description: 1MHz 400mA Step-Down Converter
• Manufacturer: AnalogicTech

Step-Down Converter Design Example
Specifications
V
V
F
T
1.8V Output Inductor
For Sumida inductor CDRH3D16, 4.7µH, DCR = 105mΩ.
1.8V Output Capacitor
V
L1 = 3
∆I
C
I
1143.2005.09.1.7
P
P
I
RMS
PKL1
S
AMB
O
IN
DROOP
L1
OUT
esr
L1
= I
= esr · I
=
=
= I
=
O
µsec
2
L1 ⋅ F
V
O
2
= 1.8V @ 400mA (adjustable using 0.6V version), Pulsed Load ∆I
= 2.7V to 4.2V (3.6V nominal)
= 1.0MHz
= 85°C
= 0.2V
3 · ∆I
·
A
DROOP
⋅ DCR = 0.4A
1
V
+
O
3
∆I
RMS
2
·
⋅ V
LOAD
L1
⋅ 1 -
(V
· F
2
⎛
⎝
= 0.4A + 0.11A = 0.51A
O2
= 5mΩ · (63mA)
O
L1 · F · V
S
) · (V
= 3
=
V
V
0.2V · 1MHz
IN
O
µsec
IN(MAX)
2
⎞
⎠
3 · 0.3A
A
⋅ 105mΩ = 17mW
=
IN(MAX)
4.7µH ⋅ 1.0MHz
⋅ 1.8V = 5.4µH
- V
O
)
1.8 V
2
= 20µW
=
= 4.5µF
2
·
1
3
·
4.7µH · 1.0MHz · 4.2V
1.8V · (4.2V - 1.8V)
⋅ 1 -
(see Table 1)
⎛
⎝
1.8V
4.2V
⎞
⎠
= 218mA
1MHz 400mA Step-Down Converter
= 63mArms
LOAD
= 300mA
AAT1143
15