Texas Instruments SLOU061A manual Maximum Power Dissipation vs Free-Air Temperature

General Power Dissipation Considerations

2.5 General Power Dissipation Considerations￿

For a given θ JA, the maximum power dissipation is shown in Figure 2–4 and is calculated by the following formula:

P	D	+￿	TMAXq–TA
			JA
Where:
PD		= Maximum power dissipation of Txxxx IC (watts)
TMAX = Absolute maximum junction temperature (150° C)
TA		= Free-air temperature (° C)
θ JA		= θ JC + θ CA

θJC = Thermal coefficient from junction to case

θCA = Thermal coefficient from case to ambient air (° C/W)

Figure 2–4. Maximum Power Dissipation vs Free-Air Temperature

MAXIMUM POWER DISSIPATION

vs

FREE-AIR TEMPERATURE

	2		SOIC (16-pin)		TJ	= 150° C
			Package
W			Low-K Test PCB
			θ JA = 114.7° C/W
–	1.5
Dissipation
					SOIC (8-pin)
					Package
					Low-K Test PCB
	1
Power
Maximum	0.5		SOIC (14-pin)
			Package
			Low-K Test PCB
	0
	–55	–25	5	35	65	95	125
		TA – Free-Air Temperature – ° C
NOTE A: Results are with no air flow and using JEDEC Standard Low-K test PCB.

Table 2–1. Dissipation Rating Table

PACKAGE	θ JC	θ JA	TA ≤ 25° C
	(° C/W)	(° C/W)	POWER RATING
D (8)	38.3	176	710 mW
D (14)	26.9	122.3	1022 mW
D (16)	25.7	114.7	1090 mW

Evaluation Module Layout 2-7