AAT2158_08 Datasheet, PDF (15/16 Pages) Advanced Analogic Technologies – 1.5A Low Noise Step-Down Converter

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PRODUCT DATASHEET
AAT2158
1.5A Low Noise Step-Down Converter
AAT2158 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 QFN
50°C/W package.
P_LOSS = I_O12 · R_DS(ON)H = 1.4A² · 0.16Ω = 0.31W
T_J(MAX) = T_AMB + Θ_JA · P_LOSS = 85°C + (50°C/W) · 310mW = 101°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]
= 1.4A² · 152mΩ + [(5ns · 1.2MHz · 1.4A + 50μA) · 3.6V] = 328mW
T_J(MAX) = T_AMB + Θ_JA · P_LOSS = 85°C + (50°C/W) · 328mW = 101°C
V_OUT (V)
3.3
3.3
2.5
1.8
1.5
1.2
1.0
0.8
0.6
Inductance
(μH)
3.0
3.3
2.2
1.8
1.8
1.2
1.0
1.0
1.0
Part Number
CDRH5D28
CDRH4D28
CDRH4D28
CDRH4D28
CDRH4D28
CDRH4D28
SD3114-1.0
SD3114-1.0
SD3114-1.0
Manufacturer
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Cooper
Cooper
Cooper
Size (mm)
6x6x3
5x5x3
5x5x3
5x5x3
5x5x3
5x5x3
3.1x3.1x1.45
3.1x3.1x1.45
3.1x3.1x1.45
Rated
Current (A)
2.4
1.57
2.04
2.2
2.2
2.56
I_RMS (A)
1.67
1.67
1.67
I_SAT
(A)
2.07
2.07
2.07
DCR (Ω)
24.0
49.2
31.3
27.5
27.5
23.6
0.042
0.042
0.042
Table 2: Surface Mount Inductors.
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
2158.2008.02.1.2
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