AAT1112 Datasheet, PDF (17/19 Pages) Advanced Analogic Technologies – 1.5A, 1.4MHz Step-Down Converter

DATA SHEET
AAT1112
1.5A, 1.4MHz Step-Down Converter
AAT1112 Losses
Total losses can be estimated by calculating the dropout (V_IN = V_O) losses where the power MOSFET R_DS(ON) will be at
the maximum value. All values assume an 85°C ambient temperature and a 120°C junction temperature with the TDFN
50°C/W package.
P_LOSS = I_O12 · R_DS(ON)H = 1.5A² · 0.16Ω = 0.36W
T_J(MAX) = T_AMB + Θ_JA · P_LOSS = 85°C + (50°C/W) · 360mW = 103°C
The total losses are also investigated at the nominal lithium-ion battery voltage (3.6V). The simplified version of the
R_DS(ON) losses assumes that the N-channel and P-channel R_DS(ON) are equal.
P_TOTAL = I_O2 · R_DS(ON) + (t_sw · F_S · I_O + I_Q) · V_IN
= 1.5A² · 152mΩ + (5ns · 1.2MHz · 1.5A + 50μA) · 3.6V = 375mW
T_J(MAX) = T_AMB + Θ_JA · P_LOSS = 85°C + (50°C/W) · 375mW = 104°C
V_OUT (V)
3.3
2.5
1.8
1.5
1.2
1.0
0.8
0.6
Inductance
(μH)
3.3
2.2
1.8
1.8
1.2
1.0
1.0
1.0
Part
Number
CDRH4D28
CDRH4D28
CDRH4D28
CDRH4D28
CDRH4D28
SD3114-1.0
SD3114-1.0
SD3114-1.0
Manufacturer
Sumida
Sumida
Sumida
Sumida
Sumida
Cooper
Cooper
Cooper
Size (mm)
5x5x3
5x5x3
5x5x3
5x5x3
5x5x3
3.1x3.1x1.45
3.1x3.1x1.45
3.1x3.1x1.45
Rated
Current
(A)
1.57
2.04
2.2
2.2
2.56
Table 2: Surface Mount Inductors.
I_RMS
(A)
I_SAT
(A)
1.67
1.67
1.67
2.07
2.07
2.07
DCR ()
36.4
23.2
20.4
20.4
17.5
0.042
0.042
0.042
Manufacturer
Murata
Murata
Part Number
GRM21BR60J106KE19
GRM21BR60J226ME39
Value
10μF
22μF
Voltage
6.3V
6.3V
Table 3: Surface Mount Capacitors.
Temp. Co.
X5R
X5R
Case
0805
0805
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
201972B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 15, 2013
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