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Analog Technologies, Inc.
ATLD201V1
Dual Mode 30MHz Modulation Laser Controller
Specifications Drive current range: Current output accuracy: Current ripple noise: Current adjustable limit: Driving mode: Temperature coefficient: Operating temperature: Storage temperature: PD feedback current: Peak power set voltage: Peak current set voltage: Modulation input voltage: Modulation input impedance: Modulation bandwidth: Power supply voltage: Power supply current: Laser diode type supported: Packaging: 0 to 120mA 2% 0.01% (RMS) and <0.1% (peak-to-peak) DC to 2KHz. 0 to 120mA Constant current and constant power 100ppm/C for power mode, 250ppm/C for current mode. -10C to 65C -40C to 85C 0.02mA to 1.5mA, 0.3mA typical 0V to 2V 0V to 2V 0V to 2V (open circuit voltage)* 50 DC to 30MHz (1dB) 5V 10% <140mA Case = laser diode cathode and photo diode anode 25mm x 20mm PCB
* The output DC and AC impedance of the modulation signal source should be 50. Pin Descriptions (See Figure 1 and 2 for laser controller ATLD201V1 views) J1: Signal Source Input. The internal conductor of the RG174 coaxial cable is for connecting to the signal source, the cable shield is for connecting the ground. J2: Power Supply Input. Pin 1, GND, power ground. Pin2, VPS, 5V power input. J3: Monitor and Programming Signals. Pin 1, LIO, laser current output, analog output. Pin 2, 2VR, voltage reference, 2V, analog output.
550 E. Weddell Drive, Suite 4, Sunnyvale, CA 94089, U. S. A. Tel.: (408) 747-9760, Fax: (408) 747-9770, Web: www.analogtechnologies.com
(c) Copyright 2000 - 2004, Analog Technologies, Inc. All Rights Reserved.
Updated: 3/24/2004
1
Analog Technologies, Inc.
Pin 3, LIS, laser current limit set voltage, both analog input and output. Pin 4, GND, signal ground. Pin 5, LPGD, loop good indication, analog output. Pin 6, SDN, shut down, digital input. Operation
ATLD201V1
1. Power up. The laser controller ATLD201V1 circuit board is shown in Figure 1 and 2. Connect the ATLD201V1 according to Figure 3. Do not insert the laser diode yet. 2. Set current limit. Look up the datasheet of the laser diode and determine the maximum current limit needs to be set. Setting the current limit to too high a value, the laser diode will not be protected properly; setting the limit to too low a value will cause the laser controller to work under constant current mode, thus losing the power modulation function. It would be wise to set the value to 1.1 times of the maximum operating current under worst conditions. For example, at the highest temperature and highest output power, the maximum current of the laser will be 100mA, set the current limit to 110mA then. This is the way to set the limit: connect a volt meter between ground (J3 pin 4) and LIS (J3 pin 3) and adjust W2 according to this formula: VP3 = 15.8*Ilim, VP4 is the voltage measured, Ilim is the current limit value to be set. For example, to set Ilim = 0.1A, VP4 = 15.8*0.1 = 1.58V. 3. Plug in the laser diode. Turn of the power supply and plug in the laser diode. Make sure the whole operation of this step is ESD protected. 4. Set maximum optical output power. Look up the datasheet of the laser diode and determine the maximum optical power. Adjust W1, measure the laser optical output power by using an optical power meter, till the maximum power is achieved. Make sure that all the laser beam is coupled into the optical power meter receiving device. At the same time, monitor LPGD (J3 pin 5), make sure that this voltage is >3V all the time. If this voltage falls below 3V, it means the laser controller is working under the current mode. When this happens, there are several reasons: A. the laser optical output power is not completely coupled into the optical power meter so that the laser power is set to a too high value on W2. B. The current limit is set to a too low value. C. The laser diode is bad.
550 E. Weddell Drive, Suite 4, Sunnyvale, CA 94089, U. S. A. Tel.: (408) 747-9760, Fax: (408) 747-9770, Web: www.analogtechnologies.com
(c) Copyright 2000 - 2004, Analog Technologies, Inc. All Rights Reserved.
Updated: 3/24/2004
2
Analog Technologies, Inc.
25mm
ATLD201V1
Laser Diode Connector
W1 J1
(mounted on the bottom side)
W2
20mm 3.2mm x 2
(Using an RG174 cable)
J2
J3
2.5mm x2 Pin 1 2.54mm Pin 1 1.27mm 2.5mm x 2
Figure 1 Top View of ATLD201V1
J1
BNC Connector RG174 cable of 200mm
0.64mm x 0.64mm x 2 0.46mm x 0.46mm x 6
W1
J2
J3
5.1mm 2.6mm 6.1mm
W2
5.1mm 2.6mm 1.65mm 1.6mm 2.35mm
Figure 2. Bottom End View of ATLD201V1
550 E. Weddell Drive, Suite 4, Sunnyvale, CA 94089, U. S. A. Tel.: (408) 747-9760, Fax: (408) 747-9770, Web: www.analogtechnologies.com
(c) Copyright 2000 - 2004, Analog Technologies, Inc. All Rights Reserved.
Updated: 3/24/2004
3
Analog Technologies, Inc.
J2 Modulation Input J1 Laser Control Circuitry J3 1 2 3 4 5 6 2 1 2V 5V 0V
ATLD201V1
50
Laser
Laser Monitor Circuitry
LIO 2VR LIS GND LPGD SDN
To ADC Voltage reference for DAC To POT or DAC Signal ground To Micro-processor To Micro-processor or a switch to ground
Figure 3. Internal Circuits and External Connections for ATLD201V1 5. Set up and Connect the Modulation Signal Source. The modulation signal has to be between 0V to 2V and the output DC and AC impedance has to be 50. Set up the modulation signal to the proper value first and then connect to J1 of ATLD201V1. When the input signal is 0V, it will generate a 1V voltage at the input pin (J1) and the output optical power is 0; when the input signal is at 2V, it will generate a 2V voltage at the input pin and the output optical power is at its maximum value. Leaving J1 unconnected will result in the input pin voltage to be at 2V and the output optical power to be at its maximum value. See Figure 3 for the internal connection of J1. 6. Monitor the laser current. The ATLD201V1 comes with a current monitor circuit. Use voltage meter or a ADC to monitor the laser current by measuring the voltage at LIO (J3 pin 1). The formula is: LI = LIO/20, LI is the laser current, LIO is the voltage at LIO (J2 pin 1). For example, when LIO is 1V, LI = 1/20 = 0.05A = 50mA. 7. Monitor the control mode. The ATLD201V1 has two control modes: constant current and constant power. Use a volt meter or ADC to monitor the control mode by measuring the voltage at LPGD (J3 pin 5). When this pin has a voltage of >3V, the controller is working under constant power mode, when this pin has a voltage of <3V, the controller is under constant current mode. 8. Shut down the controller. The ATLD201V1 can be shut down by pulling the shut down pin SDN (J3 pin 6). This pin has an internal 100K pull-up resistor, a shunt capacitor of 10nF, and a negative logic: SDN = 0 (<0.8V) turns the controller off; SDN = 1 (>1.8V) turns the controller on.
550 E. Weddell Drive, Suite 4, Sunnyvale, CA 94089, U. S. A. Tel.: (408) 747-9760, Fax: (408) 747-9770, Web: www.analogtechnologies.com
(c) Copyright 2000 - 2004, Analog Technologies, Inc. All Rights Reserved.
Updated: 3/24/2004
4
Analog Technologies, Inc.
ATLD201V1
Important Notice A. ATI gives one year warrantee for its products, except for those being damaged by excessive abuse. B. ATI reserves the right to make changes to its products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. ATI warrants performance of its products to the specifications applicable at the time of sale in accordance with A TI's standard warranty. Testing and other quality control techniques are utilized to the extent ATI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. Customers are responsible for their applications using ATI components. In order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. ATI assumes no liability for applications assistance or customer product design. ATI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of ATI covering or relating to any combination, machine, or process in which such products or services might be or are used. ATI's publication of information regarding any third party's products or services does not constitute ATI's approval, warranty or endorsement thereof. C. IP (Intellectual Property) Ownership: ATI retains the ownership of full rights for special technologies or techniques embedded in its products, the designs for mechanics, optics, plus all modifications, improvements, and inventions made by ATI for the products and/or projects.
550 E. Weddell Drive, Suite 4, Sunnyvale, CA 94089, U. S. A. Tel.: (408) 747-9760, Fax: (408) 747-9770, Web: www.analogtechnologies.com
(c) Copyright 2000 - 2004, Analog Technologies, Inc. All Rights Reserved.
Updated: 3/24/2004
5

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