Datasheet AD8145 (Analog Devices) - 8

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Data Sheet AD8145 ABSOLUTE MAXIMUM RATINGS Table 3. MAXIMUM POWER DISSIPATION Parameter Rating
The maximum safe power dissipation in the AD8145 package is Supply Voltage 12 V limited by the associated rise in junction temperature (TJ) on Power Dissipation See Figure 2 the die. At approximately 150°C, which is the glass transition Storage Temperature Range −65°C to +125°C temperature, the plastic changes its properties. Even temporarily Operating Temperature Range −40°C to +105°C exceeding this temperature limit can change the stresses that the Lead Temperature (Soldering, 10 sec) 300°C package exerts on the die, permanently shifting the parametric Junction Temperature 150°C performance of the AD8145. Exceeding a junction temperature of 150°C for an extended period can result in changes in the Stresses at or above those listed under Absolute Maximum silicon devices, potentially causing failure. Ratings may cause permanent damage to the product. This is a stress rating only; functional operation of the product at these The power dissipated in the package (PD) is the sum of the or any other conditions above those indicated in the operational quiescent power dissipation and the power dissipated in the section of this specification is not implied. Operation beyond package due to the load drive for al outputs. The quiescent the maximum operating conditions for extended periods may power is the voltage between the supply pins (VS) times the affect product reliability. quiescent current (IS). The power dissipated due to the load drive depends on the particular application. For each output, the
THERMAL RESISTANCE
power due to load drive is calculated by multiplying the load θJA is specified for the worst-case conditions, that is, θJA is current by the associated voltage drop across the device. The specified for a device soldered in the circuit board with its power dissipated due to all of the loads is equal to the sum of exposed paddle soldered to a pad on the PCB surface, which is the power dissipation due to each individual load. RMS voltages thermally connected to a copper plane. and currents must be used in these calculations.
Table 4. Thermal Resistance
Airflow increases heat dissipation, effectively reducing θJA. In
Package Type θ
addition, more metal directly in contact with the package leads
JA θJC Unit
5 mm × 5 mm, 32-Lead LFCSP 47 8.5 °C/W from metal traces, through-holes, ground, and power planes reduces the θJA. The exposed paddle on the underside of the package must be soldered to a pad on the PCB surface, which is
4.5
thermal y connected to a copper plane to achieve the specified θJA.
4.0 )
Figure 2 shows the maximum safe power dissipation in the
(W N 3.5
package vs. the ambient temperature for the 32-lead LFCSP
IO T
(47°C/W) on a JEDEC standard 4-layer board with the underside
3.0 PA
paddle soldered to a pad, which is thermally connected to a
ISSI 2.5 D
PCB plane.
ER W 2.0 M PO 1.5 ESD CAUTION MU XI 1.0 MA 0.5 0 –40 –20 0 20 40 60 80 100
002
AMBIENT TEMPERATURE (°C)
06307- Figure 2. Maximum Power Dissipation vs. Temperature for a 4-Layer Board Rev. B | Page 7 of 21 Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE MAXIMUM POWER DISSIPATION ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTION TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION APPLICATIONS INFORMATION OVERVIEW BASIC CLOSED-LOOP GAIN CONFIGURATIONS TERMINATING THE INPUT INPUT CLAMPING PCB LAYOUT CONSIDERATIONS Minimizing Parasitic Feedback Reactances Maximizing Heat Removal DRIVING A CAPACITIVE LOAD POWER-DOWN COMPARATORS SYNC PULSE EXTRACTION USING COMPARATORS OUTLINE DIMENSIONS ORDERING GUIDE AUTOMOTIVE PRODUCTS