LM6313 datasheet(9/10 Pages) NSC

9 / 10 page

Application Hints (Continued)

LASER DIODE MODULATOR

Figure 6 is a minimum component count example of a video

modulator for a CW laser diode This example biases the

diode at 200 mA and modulates the current at g200 mA per

volt of signal If it is desired to reduce power consumption

and g5V supplies are available all that is necessary is to

change R2 to 5 kX and R4 to 15X

CAPACITIVE LOAD DRIVING

Figure 7 is the circuit used to demonstrate the ability of the

LM6313 to drive capacitive loads at speeds not previously

possible with monolithic op amps

TLH10521 – 13

FIGURE 6

TLH10521 – 14

FIGURE 7

In photo 1 CL is 1000 pF The LM6313 is slewing at

250 V ms from b5V to a5V The slew rate is 450 V ms

from a5V to b5V This requires the op amp to deliver

450 mA into the load and remain stable

In photo 2 CL is changed to 1 mF Under these conditions

the op amp is forced into current limiting Here the current is

internally limited to about g400 mA Note the rapid and

complete recovery to normal operation at the end of slew-

ing

TLH10521 – 16

Photo 1

TLH10521 – 15

Photo 2

LM6313 数据表(PDF) 9 Page - National Semiconductor (TI)