IC-HT datasheet(2/45 Pages) ICHAUS

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iC-HT

DUAL CW LASER DIODE DRIVER

Rev B1, Page 2/45

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

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