PRODUCT DATASHEET
AAT1160
SwitchRegTM
12V, 3A Step-Down DC/DC Converter
AAT1160 Losses
Total losses can be estimated by calculating the dropout (VIN = VO) losses where the power MOSFET RDS(ON) will be at
the maximum value. All values assume an 85°C ambient temperature and a 140°C junction temperature with the TDFN
37°C/W package.
PLOSS = ILOAD2 · RDS(ON)H = 3A2 · 0.12Ω = 1.08W
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (37°C/W) · 1.08W = 125°C
The total losses are also investigated at the nominal input voltage (12V). The simplified version of the RDS(ON) losses
assumes that the N-channel and P-channel RDS(ON) are equal.
PTOTAL = ILOAD2 · RDS(ON) + [(tsw · FOSC · ILOAD + IQ) · VIN]
= 3A2 · 100mΩ + [(5ns · 800kHz · 3A + 150µA) · 12V] = 1.0458W
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (37°C/W) · 1.0458W = 124°C
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1160.2007.11.1.1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
