IC-WJBEVALWJ1D ICHAUS [IC-Haus GmbH], IC-WJBEVALWJ1D Datasheet - Page 6

• Manufacturer Part Number: IC-WJBEVALWJ1D
• Description: 2.7 V LASER DIODE DRIVER
• Manufacturer: ICHAUS [IC-Haus GmbH]

Laser Power Adjustment
The iC-WJB device can be adapted to CW laser diodes
of up to 40 mW. When the supply voltage is higher than
approx. 4.5 V, LD models in common cathode configu-
ration can be used.
To calculate the current required at ISET, the average
optical laser power is to determine:
with peak value P
Example for CW operation
P
diode maximum optical output of 3 mW, monitor diode
with 0.75 mA at 3 mW.
APPLICATIONS INFORMATION
iC-WJB
2.7 V LASER DIODE DRIVER
cw
24kΩ
RSET
= 1 mW (pin IN at VCC, pin CWD open), laser
4
6
ISET
IN
twhi
Figure 2: Duty cycle
peak
INPUT
P
2
av
REFERENCE
and pulse/period duration t
= P
Figure 1: Circuit diagram for LD models with a common cathode
peak
twlo
T
CWD
t
REF
2
whi
T
VCC
3
REF
POWER DOWN
WATCHDOG
THERMAL
SHUTDOWN
4
whi
/T.
470nF
CI
CI
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 averaging control of
the monitor diode current is pre-set at this pin.
At P
0.25 mA and RSET is calculated to:
with Electrical Characteristics No. 301 for V(ISET) and
No. 107 for current ratio CR1.
Example for pulse operation
Pulse duty factor t
laser diode as above with maximum optical output of
3 mW, monitor diode with 0.75 mA at 3 mW.
The average optical power is set to 0.6 mW by the
pulse duty factor; the average monitor diode current
I
to:
AV
3
RSET =
iC−WJB
is then 0.15 mA. The resistor RSET is calculated
1
av
DRIVER STAGE
GND
= P
3
1
cw
CR1 V (ISET )
1
I
= 1 mW, the monitor diode current is
av
KLD
AMD
VCC
(AMD)
whi
/T set to 20 % at P
5
8
7
C3
2nF
0..2Ω
R1
=
3 1.22 V
0.25 mA
LD
MD
Rev E1, Page 6/12
= 14.64 k
47uF
peak
C1
= 3 mW,
+5V