Analog Analog Technologies
FEATURES Ultra Low Noise: 5K. Otherwise, some error will be introduced at the output current. When the impedance is 5K, the current error caused at the output is about 0.01%. Please be aware that adding capacitor on this pin will increase the high frequency noise current. Therefore, when monitoring the output current on this pin continuously, insert a resistor of about >5K in series with the voltage meter or ADC. In this way, there is no big capacitance added on the LDC pin. Under no-fault operation conditions, the output voltage of LDC is always the same as that of LISH.
Sync. Signal (Optional) Power Supply 5V power supply 0V
7 Laser Diode
Figure 4 A Typical Micro-processor-based Application In this circuit, the input current can be set by a DAC (Digital to Analog Converter). By sensing the logic level of LPGD, pin 12, the working status of the controller can be monitored by a micro-controller (MC), when it is logic “1”, the loop is good; “0”, the loop is at fault, which includes open circuit at the laser diode connections, or short circuit from LDA to ground, but excludes short circuit at the laser diode and short circuit from LDC to ground. Shut down pin can also be controlled by the micro-controller, setting it to logic “1” turns on the controller, “0” turns it off. Please notice that this pin comes with an internal pull up resistor of 100K, it can be ORed (logic OR) by multiple digital ports of several micro-controllers, with each of the port having an opendrain output. The internal voltage reference output, 2P5V, pin 3, can be used as the reference voltage for the ADCs and the DACs. Figure 5 shows a low noise high speed square wave modulation application circuit. Figure 5 Low Noise Digital Modulation Circuit
The output current is set by adjusting W1, which sets input voltages of LISL (Laser I (current) Set Low-speed), pin 4. The output current will be: I_output = LISL(V)/2.5V (A). LISL should never be left float. Otherwise, the output current will go too high a value that the laser might be damaged. The LISL pin allows modulating the output current at a speed of up to 0.08Hz. This low speed port filters out high frequency noise, if any, in the input signal applied to this pin. In addition to using the LPGD pin for monitoring the working status of the controller, the output current can be monitored directly by measuring the voltage of LDC pin. The equation is: I_out = LDC(V)/0.5V (A).
5 5 0 E. W eddell Drive, Suit e 4 , Sunnyvale, CA 9 4089 , U. S. A . Tel.: (408) 74 7-9760 , Fax: (408 ) 7 47-977 0, Web: w w w .analogt echnologies.com
Copyrights 2000 – 2005, Analog Technologies, Inc. All Rights Reserved. Updated on 3/29/2007.
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Analog Analog Technologies
POWER UP PROCEDURE
Low Noise Constant Current Laser Driver ATLS1A102
R1.5 × 4 Orientation Mark PCB Copper without solder pad PCB Hole 19.4 2 × 14 Outline
Laser diode is a vulnerable device. Special cautions must be taken for turning on the controller. These are the recommendations: 1. Hold the SDN pin to ground by a mechanical switch or an electronic logic device when turning on the power on the VPS pin and release the SDN pin to logic high after the VPS voltage is stabilized to turn on the laser. 2. If choose not to control the SDN pin for turning on the laser, leave the SDN pin unconnected. There is an internal capacitor holding SDN pin to logic low. Now, the laser can be turned on and off by using the VPS pin. FIRST TIME POWER UP Laser is a high value and vulnerable device. Faults in connections and damages done to the controller during soldering process may damage the laser permanently. To protect the laser, it is highly recommend to use 3 regular diodes of >1A to form a “dummy laser” and insert it in the place of the real laser diode, when powering up the controller for the first time. Use an oscilloscope to monitor the LDA voltage at times of power-up and power-down, make sure that there is not over-shoot in voltage. At the same time, use an ammeter in serious with the dummy laser, to make sure that the output current is correct. After thorough checking free of faults, disconnect the dummy laser and connect the real laser in place. The controller output voltage range for the laser is between 0.5 to 4V when powered by a 5V power supply. MECHANICAL DIMENSIONS AND MOUNTING The ATLS1A102 comes in 2 packages: through hole mount and surface mount. The former is often called DIP (Dual Inline package) or D (short for DIP) package and has a part number: ATLS1A102−D, and the latter is often called SMT (Surface Mount Technology) or SMD (Surface Mount Device) package and has a part number: ATLS1A102−S.
R1.5×4 1 2 3 4 5 6 12 11 10 9 8 7 14.5 R1.5×2 Pin size: 0.5×0.5 5.0 4.0 12 Top View Side View End View
1.0 × 12
0.8 × 2 1.5 × 14
12 14.5
Figure 7 Top Side PCB Foot-print for the DIP Package
PCB Copper with solder pad
1.5 × 14 3.0 × 14
Figure 8 Top View of the Bottom Side PCB Foot-print
R1.5×4 1 2 3 4 5 6 14.5 R1.5×2 12 11 10 9 8 7 5.0
19.4 2
1.15
R1.5×2
19.4 2
Pin size: 0.5×0.5
5.6 11.5 16.8
Top View Side View End View
Figure 9 Dimensions of the SMT Package Controller
R1.5×2
Figure 6 Dimensions of the DIP Package Controller
Figure 7 shows the foot print which is seen from the top side of the PCB, therefore, it is a “see through” view. Please notice that, in the recommended foot print for the DIP package, the holes for pin 2 to 6, and 8 to 12 have larger holes than needed for the pins. This arrangement will make it easier for removing the controller from the PCB, in case there is a
5 5 0 E. W eddell Drive, Suit e 4 , Sunnyvale, CA 9 4089 , U. S. A . Tel.: (408) 74 7-9760 , Fax: (408 ) 7 47-977 0, Web: w w w .analogt echnologies.com
Copyrights 2000 – 2005, Analog Technologies, Inc. All Rights Reserved. Updated on 3/29/2007.
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Analog Analog Technologies
Low Noise Constant Current Laser Driver ATLS1A102
hold the controller in the right position.
rework needed. The two smaller holes, for pin 1 and 7, will
5 5 0 E. W eddell Drive, Suit e 4 , Sunnyvale, CA 9 4089 , U. S. A . Tel.: (408) 74 7-9760 , Fax: (408 ) 7 47-977 0, Web: w w w .analogt echnologies.com
Copyrights 2000 – 2005, Analog Technologies, Inc. All Rights Reserved. Updated on 3/29/2007.
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Analog Analog Technologies
ORDERING INFORMATION Part # ATLS1A102−D ATLS1A102−S* ATLS1A102−D−L ATLS1A102−S*−L
Low Noise Constant Current Laser Driver ATLS1A102
Description Controller in DIP package Controller in SMT package* Controller in DIP package with the switch mode driver disabled Controller in SMT package* with the switch mode driver disabled
* This surface mount package cannot be soldered by reflow oven. It must be soldered manually with the iron temperature < 610°F (≈321°C). PRICES Quantity ATLS1A102−D ATLS1A102−S ATLS1A102−D−L ATLS1A102−S−L NOTICE 1. ATI warrants performance of its products for one year to the specifications applicable at the time of sale, except for those being damaged by excessive abuse. Products found not meeting the specifications within one year from the date of sale can be exchanged free of charge. 2. 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. 3. 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. 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. 4. Customers are responsible for their applications using ATI components. In order to minimize risks associated with the customers’ applications, adequate design and operating safeguards must be provided by the customers to minimize inherent or procedural hazards. ATI assumes no liability for applications assistance or customer product design. 5. 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. 6. IP (Intellectual Property) Ownership: ATI retains the ownership of full rights for special technologies and/or techniques embedded in its products, the designs for mechanics, optics, plus all modifications, improvements, and inventions made by ATI for its products and/or projects. 1−9 10 − 49 50 − 199 200 − 999 ≥1000
$85
$75
$65
$55
$45
5 5 0 E. W eddell Drive, Suit e 4 , Sunnyvale, CA 9 4089 , U. S. A . Tel.: (408) 74 7-9760 , Fax: (408 ) 7 47-977 0, Web: w w w .analogt echnologies.com
Copyrights 2000 – 2005, Analog Technologies, Inc. All Rights Reserved. Updated on 3/29/2007.
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