ic-wkp iC-Haus, ic-wkp Datasheet - Page 6

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ic-wkp

Manufacturer Part Number
ic-wkp
Description
15 V Cw P-type Laser Diode Driver
Manufacturer
iC-Haus
Datasheet
Laser light can damage the human eye and the
eyes of animals! Do not look at any laser light di-
rectly or through any optical lens. When handling a
laser diode, do not look directly at the light generated
by it. Wear appropriate safety glasses to prevent light
from entering the eye even by reflection.
Setting the output power
The output power is simply set by RM = Vref(MDK) /
I(MD), where Vref(MDK) = Item No. 101 and I(MD) =
the monitor current of the laser diode at the desired
operating point. RM should be combined from a fixed
resistor (max. output power) and a trimmer (calibra-
tion).
Turn-on behaviour
After switching the supply voltage on, the output stage
remains disabled until the internal enabling flip-flop is
set by a sufficiently high voltage at VCC.
A quick soft start follows; the transition to controlled
CW operation is gradual and primarily determined by
the values of CI and RM. CI is properly dimensioned
when the voltage undershoot at MDK is at a minimum.
Turn-off behaviour
iC-WKP works without a fixed undervoltage lockout,
thus the laser diode forward voltage is the prime fac-
tor determining the lowest possible supply voltage.
SAFETY INSTRUCTIONS
FUNCTION DESCRIPTION
iC-WKP
15 V CW P-TYPE LASER DIODE DRIVER
VCC − 0.5V
VCC − 1.5V
VCC − 1V
V(MDK)
V(LDA)
500mV
200mA
100mA
I(LD)
V(CI)
VCC
1.5V
1.0V
2V
1V
0
0
0
0
Figure 1: Turn-on behaviour
50us
100us
Time
150us
200us
250us
If the voltage drops below this value, the output stage
is forcibly saturated and the laser current decreases.
iC-WKP simultaneously discharges control capacitor
CI so that no excessive laser diode currents occur
when the supply voltage again rises.
Disruptions in operation
The power control is shut down with excessive driver
temperature or when the laser current reaches the
overcurrent shutdown threshold, for example when the
feedback path is interrupted. If the monitor diode or
bias resistor RM fail, the device is shut down in less
than 600 µs, provided that the supply voltage applied
is high enough.
When modulating the laser current via pin MDA, low
voltage occurring at pin MDK may also cause a shut-
down.
VCC − 0.5V
VCC − 1V
V(MDK)
V(LDA)
500mV
200mA
100mA
I(LD)
VCC
1.5V
1.0V
V(CI)
2V
1V
0
0
0
Figure 2: Turn-off behaviour
1ms
Time
1,01ms
Rev A5, Page 6/8
1,02ms

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