AAT1151IKS-3.3-T1 AnalogicTech, AAT1151IKS-3.3-T1 Datasheet - Page 13

• Manufacturer Part Number: AAT1151IKS-3.3-T1
• Description: 850kHz 700mA Synchronous Buck DC/DC Converter
• Manufacturer: AnalogicTech

Design Example
Specifications
I
I
V
V
F
T
Maximum Input Capacitor Ripple:
Inductor Selection:
Select Sumida inductor CDRH3D16 3.3µH 63mΩ 1.8mm height.
Output Capacitor Ripple Current:
P = esr · I
L =
P = I
I
1151.2005.11.1.4
∆I =
Pesr = esr · I
I
I
OUT
RIPPLE
RMS
RMS
PK
S
AMB
OUT
IN
= I
I
=
=
O
V
O
L ⋅ F
2
I
⋅ k ⋅ F
OUT
2
OUT
O
V
·
⋅ DCR = (0.7)
1
O
·
0.7A
40% of Full Load at Max V
1.5V
2.7V to 4.2V (3.6V nominal)
850kHz
85°C
+
3
RMS
V
V
⋅ 1 -
·
∆I
O
2
IN
⋅ 1 -
⎛
⎝
RMS
2
V
⎛
⎝
·
= 0.7A + 0.17A = 0.87A
= 5mΩ · 0.35
OUT
⎛
⎝
1
2
V
V
-
V
= 5mΩ · 99
V
· (V
L F V
IN
OUT
O
V
V
IN
· ·
IN
O
⎞
⎠
2
IN
⎞
⎠
=
⎞
⎠
⋅ 63mΩ = 31mW
=
3.3µH ⋅ 850kHz
- V
=
0.7A ⋅ 0.4 ⋅ 850kHz
IN
0.35Arms, V
OUT
2
2
1.5 V
)
A = 0.6mW
mA = 50µW
1.5 V
=
2
·
1
IN
IN
3
·
850kHz 700mA Synchronous Buck DC/DC Converter
= 2 × V
⋅ 1-
⎛
⎝
3.3µH · 850kHz · 4.2V
1.5V · (4.2V - 1.5V)
1.5V
⋅ 1 -
4.2V
⎛
⎝
O
1.5V
4.2V
⎞
⎠
= 340mA
⎞
⎠
= 4.05µH
= 99mArms
AAT1151
13