IC-HK_1 Datasheet, PDF (10/13 Pages) IC-Haus GmbH – 155MHz LASER SWITCH

iC-HK
155MHz LASER SWITCH
Rev 21.11.01, Page 10/13
Layout advise
iC-HK can be used in a wide range of applications from CW to over 150 MHz. Very fast switches have thus been
integrated, which have to be properly blocked to prevent ringing. A small blocking capacitor is therefore required
for iC-WK between pin 2 (CI) and 3 (AGND) and also at pin 4 (CI) of iC-HK (cf. Figure 19). Increasing capacitor
CLDA might also help to suppress ringing.
If the connection between the laser diode and iC-HK (LDK Pin 7) is loaded inductively, a small capacitor CLD in
parallel with the laser diode is recommended to suppress current spikes.
With higher pulse frequencies it is advisable to use separate grounds for iC-WK, iC-HK, capacitor C1 and
resistors Rkx respectively.
The connection between VCC and LDA (dashed line) is necessary for laser currents >70mA.
Device
CVCC
CVDD
CLDA
CLD
CI
CM
C1
LED
DGND
RGND
RM
RK1
RK2
RCI
Typical value
100nF
100nF
1µF
2.2nF
47nF..
22pF
V_fw <
V(VCC_WK) -
V(GND_WK) -1V
V_fw .V(CI) - 1.7V
0S .. 100S
200S .. 50kS
0S ..
0S ..
1kS
Comment
Power supply blocking capacitor for iC-WK
Power supply blocking capacitor for iC-HK
Laser diode supply smoothing capacitor
Laser diode ESD protection, filtering with inductive loads; to be
mounted directly across the laser diode
Averaging capacitor for V(CI)-control by iC-WK
MDA smoothing capacitor, has to be calculated
CI smoothing capacitor (used with current limitation)
Load for iC-WK output stage; LED must be capable of 45mA; may be
replaced by a resistor or even jumpered
Ground shift at iC-WK to increase V(CI)
Ground shift at iC-WK to increase V(CI)
Set point of monitor current (mean value)
Set point of current through channel 1
Set point of current through channel 2
Decoupling of pin CI at iC-WK and iC-HK for laser current limitation