12

LT1630/LT1631

Q4

Q6

D6

D5

+IN

D2

Q3

Q7

Q1

+

+

Q9

Q2

D4

D1

D3

–IN

OUT

Q5

Q12

Q8

Q14

1630/31 F01

C1

R1

R6

225

Ω

R7

225

Ω

R3

R4

R5

C2

R2

Q11

Q13

Q15

BUFFER

AND

OUTPUT BIAS

Figure 1. LT1630 Simplified Schematic Diagram

Power Dissipation

The LT1630/LT1631 amplifiers combine high speed and

large output current drive in a small package. Because the

amplifiers operate over a very wide supply range, it is

possible to exceed the maximum junction temperature of

150

°C in plastic packages under certain conditions. Junc-

The power dissipation in the IC is the function of the supply

voltage, output voltage and load resistance. For a given

occurs at the maximum supply current and when the

output voltage is at half of either supply voltage (or the

maximum swing if less than 1/2 supply voltage). There-

To ensure that the LT1630/LT1631 are used properly,

calculate the worst-case power dissipation, get the ther-

mal resistance for a chosen package and its maximum

junction temperature to derive the maximum ambient

temperature.

Example: An LT1630CS8 operating on

±15V supplies and

driving a 500

Ω, the worst-case power dissipation per

amplifier is given by:

= 0.143 + 0.113 = 0.256W

If both amplifiers are loaded simultaneously, then the total

power dissipation is 0.512W. The SO-8 package has a

junction-to-ambient thermal resistance of 190

°C/W in still

air. Therefore, the maximum ambient temperature that the

part is allowed to operate is:

For a higher operating temperature, lower the supply

voltage or use the DIP package part.