AAT1162 View Datasheet(PDF) - Advanced Analogic Technologies
Part Name
Description
MFG CO.
'AAT1162' PDF : 18 Pages View PDF
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PRODUCT DATASHEET
AAT1162
12V, 1.5A Step-Down DC/DC Converter
AAT1162 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 = 1.5A2 · 0.158Ω = 0.355W
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (37°C/W) · 355mW = 96.6°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]
= 1.5A2 · 100mΩ + [(5ns · 800kHz · 1.5A + 150µA) · 12V] = 299mW
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (37°C/W) · 299mW = 96°C
1162.2008.01.1.3
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