ZHCSSK0N june 2010 – july 2023 TPS2041B , TPS2042B , TPS2043B , TPS2044B , TPS2051B , TPS2052B , TPS2053B , TPS2054B
PRODUCTION DATA
The low on-resistance on the N-channel MOSFET allows the small surface-mount packages to pass large currents. The thermal resistances of these packages are high compared to those of power packages; it is good design practice to check power dissipation and junction temperature. Begin by determining the rDS(on) of the N-channel MOSFET relative to the input voltage and operating temperature. As an initial estimate, use the highest operating ambient temperature of interest and read rDS(on) from Figure 7-35. Using this value, the power dissipation per switch can be calculated by Equation :
Multiply this number by the number of switches being used. This step renders the total power dissipation from the N-channel MOSFETs.
Finally, calculate the junction temperature with Equation :
where
Compare the calculated junction temperature with the initial estimate. If they do not agree within a few degrees, repeat the calculation, using the calculated value as the new estimate. Two or three iterations are generally sufficient to get a reasonable answer.