Electronic Design

Laser Diode Controller Targets Fiber-Optic Applications

To precisely control the bias and modulation current of laser diodes in fiber-optic applications, Xicor's X9530 integrated controller incorporates two digitally controlled current sources or sinks.

Each of the X9530's two 8-bit current output digital-to-analog converters (DACs) is temperature compensated with 64- by 8-bit lookup tables. Hence, users can independently program the DACs' output current to vary with temperature in accordance with the contents of the associated nonvolatile EEPROM lookup tables. The controller also offers a 2176-bit supplementary EEPROM array for storing manufacturing data and other system parameters. Users can then program the lookup table or modify the setup data via the two-wire serial port.

The controller lets users maintain constant optical power over temperature. By avoiding excessive currents caused by temperature drifts, the device extends a laser diode's lifetime. Both current generators can be driven using either the on-chip temperature sensor or an external sensor. Operating temperature ranges from −40°C to 100°C, resulting in 2.2°C/step resolution. Maximum output current is ±1.6 mA. And, the X9530 offers write protection and operates from a 3- to 5.5-V supply.

Packaging options include a 14-pin TSSOP or a 15-lead XBGA. In lots of 10,000, the X9530 in the TSSOP costs $4.70.

Xicor Inc., www.xicor.com; (408) 546-3564; fax: (408) 432-0640.

>See associated figure

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