Integrated laser diode driver for digital control

Louise Smyth

The new laser diode driver iC-HTG  from iC-Haus enables single-channel microcontroller-based control of laser diodes or LEDs with common cathode (P-type) or common anode (N-type) or individual anodes/cathodes in CW mode. Optionally, either the optical output power (via APC), the laser diode current (using ACC), or a fully controller-based control can be used to control the laser diodes. 

The laser diode current is measured with the voltage drop at the shunt. The maximum laser diode current per channel is defined via an external power transistor and is scalable across a wide range from a few mA. In addition, an automatic overcurrent shutdown is adjustable. Due to the high integration of the analogue functions for controlling and regulating the laser diodes with the microcontroller interface, powerful laser diode controllers can be implemented easily and compactly. In addition to the iC- HTG, a compatible power transistor, and a shunt, a microcontroller and the laser diode or LED are required.

Internal operating points and various voltages can be output via analog-digital converters. The integrated temperature sensor allows monitoring of the system temperature for feedback in the control loop.

Logarithmic digital-to-analog converters provide optimal optical power control across a wide dynamic range for a variety of applicable laser diodes and LEDs. The respective configuration is stored in two equivalent memory areas. Internal current limits, supply voltage monitoring, an interruption switch input, and a watchdog ensure operation of the laser diode or LED via the iC-HTG. The device is controlled via an SPI or I2C interface. An analog modulation for frequencies up to 50 kHz is possible.

An external power supply can be controlled via the current output DCO in order to reduce the power dissipation of the system to a minimum, desirable if used in battery powered devices or systems.

The design-in process is supported with ready-to-use demo boards and software for evaluation with the PC.