DAC8750IPWPR datasheet(40/53 Pages) TI1

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DAC7750, DAC8750

SBAS538B – DECEMBER 2013 – REVISED JUNE 2016

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11.3 Thermal Considerations

The DACx750 is designed for a maximum junction temperature of 150°C. In cases where the maximum AVDD is

driving maximum current into ground, this junction temperature can be exceeded. Use Equation 7 to determine

the maximum junction temperature that can be reached.

Power dissipation = (TJ max – TA) / θJA

where

•

TJ max = 150°C

•

TA is the ambient temperature

•

θJA is the package-dependent, junction-to-ambient thermal resistance, found in Thermal Information.

(7)

The power dissipation is calculated by multiplying all the supply voltages with the currents supplied, which are

found in the Power Requirements subsection of Electrical Characteristics.

Consider an example: IOUT is enabled, supplying 24 mA into GND with a 25°C ambient temperature, AVDD of

24 V, and DVDD is generated internally. From the Electrical Characteristics, the max value of AIDD = 3 mA when

IOUT is enabled and DAC code = 0x0000. Also, the max value of DIDD = 1 mA. Accordingly, the worst-case

power dissipation is 24 V × (24 mA + 3 mA + 1 mA) = 672 mW. Using the θJA value for the TSSOP package, we

get TJ max = 25°C + (32.3 × 0.672)°C = 46.7°C. At 85°C ambient temperature, the corresponding value of TJ

max is 106.7°C. Using this type of analysis, the system designer can both specify and design for the equipment

operating conditions. Note that for enhanced thermal performance, connect the thermal pad in both packages to

a copper plane.

DAC8750IPWPR Datasheet(PDF) 40 Page - Texas Instruments