SLVSAA0E November 2010 – March 2020 TPS7A6201-Q1
PRODUCTION DATA.
Refer to the PDF data sheet for device specific package drawings
Calculate the power dissipated in the device using Equation 3.
where
As IQUIESCENT << IOUT, therefore, the term IQUIESCENT × VIN in Equation 3 can be ignored.
For device under operation at a given ambient air temperature (TA), calculate the junction temperature (TJ) Equation 4.
where
Calculate the rise in junction temperature due to power dissipation using Equation 5.
For a given maximum junction temperature (TJ-Max), calculate the maximum ambient air temperature (TA-Max) at which the device can operate using Equation 6.
Example
If IOUT = 100 mA, VOUT = 5 V, VIN = 14 V, IQUIESCENT = 250 µA, and RθJA = 30˚C/W, the continuous power dissipated in the device is 0.9 W. The rise in junction temperature due to power dissipation is 27˚C. For a maximum junction temperature of 150˚C, maximum ambient air temperature at which the device can operate is 123˚C.
For adequate heat dissipation, TI recommends soldering the thermal pad (exposed heat sink) to thermal land pad on the PCB. Doing this provides a heat conduction path from die to the PCB and reduces overall package thermal resistance. Figure 22 illustrates the power derating curves for the TPS7A6201-Q1 device in the KTT (TO-263) package..
For optimum thermal performance, TI recommends using a high-K PCB with thermal vias between ground plane and solder pad or thermal land pad. This is shown in Figure 23 (a) and (b). Furthermore, heat spreading capabilities of a PCB can be considerably improved by using a thicker ground plane and a thermal land pad with a larger surface area.
Keeping other factors constant, surface area of the thermal land pad contributes to heat dissipation only to a certain extent. Figure 24 shows a variation of RθJA with surface area of the thermal land pad (soldered to the exposed pad) for KTT package.