Continuous Wave Laser a Average Power Controller ADN2830 FEATURES GENERAL DESCRIPTION Bias Current Range 4 mA to 200 mA The ADN2830 provides closed-loop control of the average Monitor Photodiode Current 50 A to 1200 A optical power of a continuous wave (CW) laser diode (LD) Closed-Loop Control of Average Power after initial factory setup. The control loop adjusts the laser Laser FAIL and Laser DEGRADE Alarms IBIAS to maintain a constant back facet monitor photodiode Automatic Laser Shutdown, ALS (MPD) current and thus a constant laser optical power. The Full Current Parameter Monitoring external PSET resistor is adjusted during factory setup to set 5 V Operation the desired optical power. R is set at 1.23/I , where I PSET AV AV 40 C to +85 C Temperature Range is the MPD current corresponding to the desired optical power. 5 mm 5 mm 32-Lead LFCSP Package Programmable alarms are provided for laser fail (end of life) and laser degrade (impending fail). APPLICATIONS To provide monitoring of the MPD current, the MPD can be Fiber Optic Communication connected to the IMPD pin. In this case, the MPD current is mirrored to the IMPDMON pin to provide a monitor and internally to the PSET pin to close the control loop. By closing the feedback using IBMON rather than an MPD connected to PSET, the device is configured to control a constant current in the laser rather than a constant optical output power. FUNCTIONAL BLOCK DIAGRAM IBMON IMPDMON ALS FAIL DEGRADE MODE V GND CC V V CC CC MPD LD IMPD GND IBIAS CONTROL PSET ASET R PSET R ASET GND GND PAVCAP GND B REV.REV. Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. may result from its use. No license is granted by implication or otherwise Tel: 781/329-4700 www.analog.com under any patent or patent rights of Analog Devices. Trademarks and 781/461-3113 2012 registered trademarks are the property of their respective companies. Fax: Analog Devices, Inc. All rights reserved.1 (V = 5 V 10%. All specifications T to T , unless otherwise noted . CC MIN MAX ADN2830SPECIFICATIONS Typical values as specified at 25 C.) Parameter Min Typ Max Unit Conditions/Comments LASER BIAS (BIAS) Output Current IBIAS 4 200 mA Compliance Voltage 1.2 V V CC IBIAS during ALS 40 A ALS Response Time 10 s MONITOR PD (IMPD) Current 50 1200 A Input Voltage 1.6 V POWER SET INPUT (PSET) Capacitance 80 pF Input Current 50 1200 A Voltage 1.15 1.23 1.35 V ALARM SET (ASET) Allowable Resistance Range 1.2 13 k Voltage 1.15 1.23 1.35 V Hysteresis 5 % LOGIC INPUTS (ALS, MODE) V 2.4 V IH V 0.8 V IL ALARM OUTPUTS (Internal 30 k Pull-Up) V 2.4 V OH V 0.4 V OL IBMON IMPDMON IBMON, Division Ratio 100 A/A IMPDMON Division Ratio 1 A/A Compliance Voltage 0 V 1.2 V CC SUPPLY 2 I 25 mA IBIAS = 0 CC V 4.5 5.0 5.5 V CC NOTES 1 Temperature range: 40C to +85C. 2 I for power calculation is the typical I given. CC CC Specifications subject to change without notice. 2 REV. B