AAT1112ITP-0.6-T1 View Datasheet(PDF) - Analog Technology Inc
Part Name
Description
MFG CO.
'AAT1112ITP-0.6-T1' PDF : 20 Pages View PDF
AAT1112
1.5A, 1.4MHz Step-Down Converter
Design Example
Specifications
VO 3.3V @ 1.5A, Pulsed Load ΔILOAD = 1.5A
VIN 2.7V to 4.2V (3.6V nominal)
FS 1.2MHz
TAMB 85°C in TDFN33-12 Package
Output Inductor
L1 = VO(µH) = 3.3µH; see Table 2.
For Sumida inductor CDRH4D28 3.3µH DCR = 49.2mΩ max.
ΔI1 =
VO
L1 ⋅ FS
⋅
⎛⎝1
-
VO1⎞
VIN ⎠
=
3.3V
3.3µH ⋅ 1.2MHz
⋅
⎛⎝1 -
3.3V ⎞
4.2V ⎠
= 179mA
IPK1
=
IO1
+
ΔI1
2
=
1.5A
+
0.089A
=
1.59A
PL1 = IO12 ⋅ DCR = 1.5A2 ⋅ 49.2mΩ = 110mW
Output Capacitor
VDROOP = 0.2V
COUT
=
3 · ΔILOAD
VDROOP · FS
=
3 · 1.5A
0.2V · 1.2MHz
= 18.8µF; use 22µF
I = RMS(MAX)
1
2·
· (VOUT) · (VIN(MAX) - VOUT)
3
L · FS · VIN(MAX)
=1
2·
3
·
3.3V · (4.2V - 3.3V)
3.3µH · 1.2MHz · 4.2V
= 52mArms
Pesr = esr · IRMS2 = 5mΩ · (52mA)2 = 13.3µW
16
1112.2007.01.1.1
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