iC-HT
DUAL CW LASER DIODE DRIVER
nar y
limi
pre
Rev A1, Page 2/42
DESCRIPTION
Dual CW laser diode driver iC-HT can operate two in-
dividual laser diodes with up to 750 mA laser current
depending on the heat dissipation. Each channel can
be enabled independently. The laser diode driver can
be controlled by an external microcontroller (MCU
mode) or operate stand alone with pin/resistor config-
uration (iC-WK mode). In MCU mode, both channels
can be combined for driving up to 1500 mA.
Each channel can be operated individually either in
automatic current control (ACC) or automatic power
control (APC). All parameters including the internal
reference voltages are set via serial communication
(I²C or SPI). A 10 bit resolution D/A converter with
logarithmic characteristic is used for setting the oper-
ating point. This allows an operating point resolution
better than 1%.
In APC control, the monitor diode photocurrent is
used to track the optically emitted power of the laser
diode. The feedback for the laser diode driver is the
voltage of the photocurrent at a monitor resistor. An 8
bit internal programmable logarithmic monitor resis-
tor (PLR) or an external monitor resistor can be se-
lected for closing the control loop. The PLR ranges
from 100
Ω
to 500 kΩ with a step width less than 5%.
In ACC control, the laser diode current can be set
directly. Two current ranges are selectable.
iC-HT allows disabling the laser channels when an
overcurrent threshold has been exceeded. The over-
current threshold of each channel has 2 ranges and
is programmable through an 8 bit linear D/A con-
verter.
The temperature monitor measures the internal chip
temperature. iC-HT disables the laser channels
when overtemperature is detected.
A variety of voltages can be measured with a 10 bit
A/D converter. The following voltages can be mea-
sured:
•
•
•
•
•
V(LDKx)
V(VDD)
V(VB)
V(MDAx)
V(PLRx)
The DCO current output pin can control an external
DC/DC converter. Controlling the DC/DC output volt-
age can optimize the power dissipation of the whole
system e.g. to extend battery life.
iC-HT in standby mode has a very low current con-
sumption (< 10 µA) and does retain its configuration.
The device features for
safe operation:
•
•
•
•
Configuration verification
Tri-state configuration pins
Write protection in operating mode
Safe default/startup state
ICHAUS [ IC-HAUS GMBH ]
