Hi Ti,
There is a requirement of Vin: 5V and Vout:3.3V@1A. Looking for LDO based regulator and currently looking at TPS746. Looking at the RθJA it's about 80.3°C/W where this is the concern on heat as the losses estimated at 1.7W from 5V to 3.3V.
Can you share whether can we still consider the TPS746? Thanks.
Hi ,
While the Thermal Information table provides data that can be used as a first pass thermal check, keep in mind that with proper layout you may achieve better thermal performance than the JEDEC hi-k board on which the Thermal Information table is modeled. The primary heatsink for TPS746, like most LDOs, is the GND plane of the PCB. As such, maximizing the GND copper connected to the thermal pad within your application constraints will yield the best thermal performance for your application.
That being said, 1.7 W is a lot of power to dissipate in a small package such as the 2 mm x 2 mm WSON. You may want to consider providing a mid rail between 5 V and 3.3 V. You can do this efficiently with a dcdc switching regulator reducing your power consumption, with two LDOs in series increasing your system PSRR, or even with a power resistor in series before the TPS746. The last two will not reduce your power consumption; however, they will spread the dissipation and reduce the junction temperature of the TPS746.
If you are unable to reduce the input voltage seen by the TPS746 by creating a mid rail, you should consider another linear regulator with a lower RθJA. Due to the fact that simulates the Thermal Information table the same way on a standardized JEDEC hi-k board for every linear regulator, you can directly compare the thermal metrics between two TI linear regulators to get a better sense of which linear regulator will perform better thermally. You can make these comparisons on our parametric search at
Very Respectfully,
Ryan
