IC-HK_1 参数 Datasheet PDF下载

iC-HK

155MHz LASER SWITCH

Rev 21.11.01, Page 9/13

Laser current limitation without an iC-WK shutdown

Another way of providing protection against overcurrent is illustrated in Figure 19. With increasing current

through RK1 transistor Q1 is switched on, lowering the voltage at CI and thus reducing the laser current without

triggering iC-WK‘s overcurrent shutdown.

VCC

LDA

TRANSIENT

PROTECTION

MDK

MDA

LDK

VREF

0.5V

VDD

-

+

1

CI

D

LDK

CI

EN1

NQ

R

iC-WK

OVERCURRENT

FEEDBACKMON./

OVERTEMP.

AGND

AGND1

AGND2 GND

EN2

GND

Fig. 19: Laser current limitation without an iC-WK shutdown

Caution:

Due to the direct feedback of the controlled current through RKx to the control voltage at CI there is a

certain tendency towards oscillation. This can be counteracted by experimenting with the settings of the

components involved.

Hint:

Please bear in mind that the laser characteristic

of most laser diodes has a strong temperature

dependency, in particular with regard to threshold

current (I

th

) and efficiency. To avoid damage to the

laser diode sufficient cooling has to be provided

and/or protection against overcurrent implemented as

shown above.

Fig. 20: Temperature dependency of the laser

bias