The data sheets for the ADM7170, ADM7171 and the ADM7172 all list the same thermal resistances even though their rated currents are 0.5A, 1.0A and 2.0 respectively. How can this be so if their maximum junction temperatures are all the same?
The difference in current ratings for ADM7170, ADM7171 and ADM7172 is due to their difference in "Current-Limit Threshold" which is shown in the specification table of the data sheet. If you will notice in the specifications table, the current-limit threshold for ADM7170 is 1.3A(typical), 2.1A(typical) for ADM7171 and 3.3A(typical) for ADM7172. The part has internal registers which include the registers for current-limit threshold that are trimmed accordingly depending on what output current the part is programmed to operate.
The data sheets for ADM7170, ADM7171 and ADM7172 have the same thermal resistances because they are of the same die with the same IC package. Thermal resistances are dependent on the IC package and the difference on current ratings has no effect on the thermal resistance.
Thank you for your response. If the ADM7170, ADM7171 and ADM7172 use the same die and the same package, then how can they have the different current ratings?
Thank you for explaining that.
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