iC-VJ, iC-VJZ
LASER DIODE CONTROLLER
Rev A1, Page 6/10
DESCRIPTION OF FUNCTIONS
Laser Power Adjustment
Example iC-VJ
The iC-VJ and iC-VJZ devices can be adapted to CW Laser diode with 5 mW maximum optical output, mon-
laser diodes from 2 to 40 mW. Models can be used in itor diode with 0.13 mA/mW, average power 1 mW
which the cathode of the monitor diode is connected to (peak power 2 mW; pulse duty ratio Twhi / T is 50%).
the anode or the cathode of the laser diode.
RSET is calculated as:
The driver output, pin KLD, permits laser diode cur-
rents of up to 250 mA. In the event of a thermal over-
load due to excessive high power dissipation, the
driver is turned off.
CR1∗V(ISET) 1∗1.22V
RSET =
=
≈ 9.4kΩ
0.13mA
I(AMD)
with the Electrical Characteristics No. 501 for V(ISET)
and with No. 107 for current ratio CR1.
The pin ISET is used for the adjustment to the sensi-
tivity of the monitor diode and to set the desired optical
laser power. The setpoint for the average control of the
monitor diode current is preset at this pin, by connect-
ing it either to a resistor or a current source.
Example iC-VJZ
Laser diode with 5 mW maximum optical output, mon-
itor diode with 0.75 mA at 3 mW, average power 1 mW
(peak 2 mW; pulse duty ratio Twhi / T is 50%).
When connected to a current source, by means of an
operational amplifier with current output (OTA) for ex-
ample, the laser power can also be modulated. In or-
der to limit the current at pin ISET when turning on the
supply for the OTA, however, the OTA output should be
connected to the base point of RSET.
For the average monitor current of 0.25 mA the resistor
RSET is calculated as:
CR1∗V(ISET) 3∗1.22V
RSET =
=
≈ 14.6kΩ
0.25mA
I(AMD)
The maximum current possible at ISET must be taken
into consideration when dimensioning the capacitor with the Electrical Characteristics No. 501 for V(ISET)
C2.
and with No. 107 (iC-VJZ) for current ratio CR1.
Sync
DC−Monitor
5V
R3
C3
10kΩ
100nF
13
4
12
VCC
C4
MO
MI
100µF
DRIVER
OUTPUT
DIVIDER
16:1
LD
Q
1
14
15
PRF
NQ
MD
AMD
NQ
NPRF
MONITOR
7
4
2
1:1 iC−VJ
1:3 iC−VJZ
POWER ON
TH−SHUTDOWN
REFERENCE
KLD
OSCILLATOR
GND
3
3
5
6
iC−VJ/VJZ
R
5
RC
6
ISET
AGND
CI
9
11
7
RSET
R1
C2
800Ω
470nF
C1
100pF
Figure 1: Operation of a laser diode according to the example
ICHAUS [ IC-HAUS GMBH ]
