Datasheet LT1630, LT1631 (Analog Devices) - 15

LT1630/LT1631 applicaTions inForMaTion V+ R3 R4 R5 + Q12 I1 Q11 Q13 Q15 D1 R6 +IN 225Ω + Q5 VBIAS I2 C2 D2 D5 D6 R7 –IN V– CC OUT 225Ω Q4 Q3 Q1 Q2 D3 BUFFER Q9 AND Q8 D4 OUTPUT BIAS C1 Q7 Q6 Q14 V– R1 R2 1630/31 F01
Figure 1. LT1630 Simplified Schematic Diagram Power Dissipation
To ensure that the LT1630/LT1631 are used properly, calculate the worst-case power dissipation, get the ther- The LT1630/LT1631 amplifiers combine high speed and mal resistance for a chosen package and its maximum large output current drive in a small package. Because junction temperature to derive the maximum ambient the amplifiers operate over a very wide supply range, it temperature. is possible to exceed the maximum junction temperature of 150°C in plastic packages under certain conditions. Example: An LT1630CS8 operating on ±15V supplies and Junction temperature, TJ, is calculated from the ambient driving a 500Ω, the worst-case power dissipation per temperature, TA, and power dissipation, PD, as follows: amplifier is given by: LT1630CN8: TJ = TA + (PD • 130°C/W) PDMAX = (30V • 4.75mA) + (15V – 7.5V)(7.5/500) LT1630CS8: TJ = TA + (PD • 190°C/W) = 0.143 + 0.113 = 0.256W LT1631CS: TJ = TA + (PD • 150°C/W) If both amplifiers are loaded simultaneously, then the The power dissipation in the IC is the function of the total power dissipation is 0.512W. The SO-8 package has supply voltage, output voltage and load resistance. For a junction-to-ambient thermal resistance of 190°C/W in a given supply voltage, the worst-case power dissipation still air. Therefore, the maximum ambient temperature that PDMAX occurs at the maximum supply current and when the part is allowed to operate is: the output voltage is at half of either supply voltage (or the T maximum swing if less than 1/2 supply voltage). Therefore A = TJ – (PDMAX • 190°C/W) T P A = 150°C – (0.512W • 190°C/W) = 53°C DMAX is given by: For a higher operating temperature, lower the supply PDMAX = (VS • ISMAX) + (VS/2)2/RL voltage or use the DIP package part. 16301fa Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Applications Information Package Description Typical Application Related Parts