AAT1150 Advanced Analogic Technologies, AAT1150 Datasheet - Page 14

• Manufacturer Part Number: AAT1150
• Description: 1MHz 1A Step-Down DC/DC Converter
• Manufacturer: Advanced Analogic Technologies

Design Example
Specifications
I
I
V
V
F
Maximum Input Capacitor Ripple
Inductor Selection
Select Sumida inductor CDRH5D18, 4.1µH, 57mΩ, 2.0mm height.
Output Capacitor Dissipation
P = ESR
L =
P = I
I
P
14
I
∆I =
I
OUT
RIPPLE
RMS
RMS
PK
s
OUT
IN
ESR
= 830kHz
= I
= 2.7V to 4.2V (3.6V nominal)
I
= I
= 1.0A
O
=
O
= ESR
= 1.5V
L ⋅ F
V
OUT
2
⋅ k ⋅ F
V
2
= 30% of Full Load at Max V
O
OUT
⋅ DCR = 57mW
O
⋅
⋅
1
COUT
+
3
⋅ 1 -
∆I
COUT
2
⋅
V
V
⎛
⎝
⋅ 1 -
⋅ I
V
O
IN
= 1.0A + 0.14A = 1.14A
⎛
⎝
RMS
OUT
⋅ I
V
⋅ 1-
V
⎛
⎝
L ⋅ F ⋅ V
RMS
2
V
IN
V
O
⋅ (V
= 5mΩ ⋅ 0.5
OUT
IN
⎞
⎠
2
V
V
=
IN
= 5mΩ ⋅ 0.082
⎞
⎠
IN
O
- V
⎞
⎠
=
4.1µH ⋅ 830kHz
IN
=
1.0A ⋅ 0.3 ⋅ 830kHz
OUT
I
2
O
1.5 V
)
= 0.5A
2
=
A = 1.25mW
1.5 V
2
⋅
1
IN
2
3
A = 33µW
RMS
⋅
4.1µH ⋅ 830kHz ⋅ 4.2V
, V
1.5V ⋅ (4.2V - 1.5V)
⋅ 1-
⎛
⎝
IN
= 2 × V
1.5V
4.2V
⋅ 1 -
⎛
⎝
⎞
⎠
= 280mA
1.5V
4.2V
O
1MHz 1A Step-Down DC/DC Converter
⎞
⎠
= 3.9µH
= 82mA
RMS
AAT1150
1150.2005.03.1.2