IC-HGP Datasheet, PDF (10/20 Pages) IC-Haus GmbH – 3A HIGH-SIDE LASER SWITCH

iC-HGP
3 A HIGH-SIDE LASER SWITCH
LASER OUTPUTS LDA1...6
LDA1...6 are the current outputs for the laser diode an-
ode. For high speed operation, connect the laser diode
as close as possible to this pins to minimize the induc-
tance. To ensure a high switching speed, it is important
to minimise the inductance of the whole current loop
including the backup capacitors.
It may still be necessary though to use an R/C snubber
network for damping L/C oscillations.
Figure 7 shows the typical output characteristics of LDA.
The left side of the diagram is the RDSon region where
the current depends strongly on the voltage at LDA.
The right side of the diagram is the current source re-
gion where the current depends only somewhat on the
voltage at LDA. Only the current source region should
be used.
preliminary
Rev A1, Page 10/20
Figure 7: Typical output characteristics of LDA
PULSED OPERATION
The current for pulsed operation may be higher than for
CW operation. Therefore the RMS current of the pulse
train has to be considered.
With I_CWmax from Electrical Characteristics No. 101 and
pulses < 10 µs. So for a single channel operated with a
50% duty cycle, the max. laser current becomes
repetition time(T)
I_pulsemax = I_CWmax ·
pulse time(t)
(1)
√
I_pulsemax = 500 mA · 2 = 707 mA
LASER AND SWITCH SUPPLIES VBL and VNBL
The independent power supplies for the lasers are sep-
arated into 3 groups of 2 channels:
VBL12 is the laser supply for channel 1 and 2.
VBL34 is the laser supply for channel 3 and 4.
VBL56 is the laser supply for channel 5 and 6.
The power supply pins for the fast laser switch are
VBL and VNBL. The power supply voltage from VBL to
VNBL is a mirror of the voltage from VDD to GND and
internally generated:
VNBL12 relates to VBL12.
VNBL34 relates to VBL34.
VNBL56 relates to VBL56.
An external capacitor between VBL and VNBL is used
to stabilize this power supply. For laser supplies VBL
up to 5.5 V the corresponding VNBL can be connected
directly to GND and the capacitor can be omitted. An
example for separated power supplies and VBL56 up
to 5.5 V can be found on page 16: "6 channel TTL fast
with 3 separated power supplies".
ERROR OUTPUT NER
The open drain pin NER is a low-active error output.
Signalled errors are ELVDS open or at 50% VDD, VDD
undervoltage and thermal shutdown.