IC-VJ Datasheet, PDF (6/10 Pages) IC-Haus GmbH – LASER DIODE CONTROLLER

iC-VJ, iC-VJZ
LASER DIODE CONTROLLER
DESCRIPTION OF FUNCTIONS
Rev A1, Page 6/10
Laser Power Adjustment
The iC-VJ and iC-VJZ devices can be adapted to CW
laser diodes from 2 to 40 mW. Models can be used in
which the cathode of the monitor diode is connected to
the anode or the cathode of the laser diode.
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.
Example iC-VJ
Laser diode with 5 mW maximum optical output, mon-
itor diode with 0.13 mA/mW, average power 1 mW
(peak power 2 mW; pulse duty ratio Twhi / T is 50%).
RSET is calculated as:
CR1 ∗ V (ISET ) 1 ∗ 1.22 V
RSET = _I(AMD) = _{0.13 mA} ≈ 9.4 k Ω
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.
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.
with the Electrical Characteristics No. 501 for V(ISET)
and with No. 107 for current ratio CR1.
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%).
For the average monitor current of 0.25 mA the resistor
RSET is calculated as:
CR1 ∗ V (ISET ) 3 ∗ 1.22 V
RSET =
=
≈ 14.6 k Ω
I(AMD)
0.25 mA
The maximum current possible at ISET must be taken
into consideration when dimensioning the capacitor
C2.
with the Electrical Characteristics No. 501 for V(ISET)
and with No. 107 (iC-VJZ) for current ratio CR1.
Sync
DC−Monitor
13
MO
R3
10k Ω
C3
100nF
4
12
MI
VCC
14
PRF
15 _NPRF
OUTPUT
2
DIVIDER
Q
16:1
NQ
NQ
4
OSCILLATOR
REFERENCE
7
MONITOR
POWER ON
TH−SHUTDOWN
DRIVER
1
AMD
1:1 iC−VJ
1:3 iC−VJZ
KLD
3
5
6
GND 3
R
5
R1
800 Ω
RC
6
C1
100pF
iC−VJ/VJZ ISET
CI AGND
11
9
7
RSET
C2
470nF
5V
C4
100 µF
LD
MD
Figure 1: Operation of a laser diode according to the example