155 MHz LASER SWITCH

Rev F1, Page 2/8

DESCRIPTION

Laser Switch iC-HK/B enables the spike-free switch-

ing of laser diodes with well-defined current pulses at

frequencies ranging from DC to 155 MHz.

The diode current is determined by the voltage at

pin CI and by the resistors RK1 and RK2. The two

fast switches are controlled independently via CMOS

inputs EN1 and EN2. The laser diode can thus be

turned on and off or switched between different cur-

rent levels defined by the ratio of RK1 and RK2.

Each channel can be operated on 150 mA DC and

up to 700 mA pulsed current depending on the fre-

quency, duty cycle and heat dissipation.

The integrated thermal shutdown feature prevents

damage from excessive temperature.

iC-HK/B supplements the laser diode driver iC-WK

which uses the monitor current of the laser diode to

control the laser power. iC-WK therefore controls the

voltage at pin CI in such a way that the mean value

of the emitted laser power is constant (APC), pro-

viding there is a constant duty cycle and a switching

frequency higher than 100 kHz.

OVERTEMP.−

SHUTDOWN

iC−HK/B

CI

LDK

EN1

EN2

AGND2

AGND1

GND

8

3

1

5

4

2

6

VDD

7

LD

RK1

RK2

CLDA

M2

M1

+3.5..5 V

V(CI)

Figure 1: Operation as a voltage-controlled cur-

rent source

TRANSIENT

OVER CURRENT

R

AGND

LDK

MDK

CI

MDA

NQ

LDA

GND

VCC

PROTECTION

+

−

D

1

OVERTEMP.

iC−WK

FEEDBACK MON./

0.5 V

VREF

8

3

1

5

4

2

6

7

100 nF

CVCC

47 nF..

CI

1 uF

CLDA

MD

LD

+3.5..5 V

0 V

1

RM

200

Ω..50 kΩ

6

0..

RK2

LED

RGND

CM

CLDA

2.2 nF

CLD

M1

M2

EN2

DGND

0..

RK1

LDK

VDD

EN1

EN2

iC−HK/B

AGND1

AGND2

GND

CI

OVERTEMP.−

SHUTDOWN

CVDD

EN1

100 nF

Figure 2: Operation of iC-HK/B in conjunction with CW driver iC-WK (see application information on

optional parts/connections)