LDD P Series Laser Diode Drivers

Transcription

1 Laser Diode Drivers Low Noise Driver for Laser Diodes GENERAL DESCRIPTION: The of laser diode drivers come in three compact models to work with all laser diode / photodiode confi gurations. Each model is available in 00 and 00 versions to best fi t your laser diode requirements. When it is essential to have high performance in your application, these low noise drivers offer excellent current stability in constant current mode or <0.0% power stability in constant power mode. Precisely control the laser diode or photodiode setpoint current with the onboard Current Adjust trimpot or via a remote voltage to the modulation input. The modulation input s small signal db bandwidth is DC to MHz in constant current mode and dependent on photodiode speed in constant power mode. Measure laser diode and photodiode current from two buffered monitor outputs. September, 009 FEATURES: Up to 00 Current Drive Capacity Operates in Constant Current or Constant Power Modes to Single supply operation power stability < 0.0% typical ( hours, ambient conditions Turn Trimpots control Current Setpoint and Limit Setpoint Operates all low power Laser Diodes Constant Current Modulation to MHz Slow start circuitry Buffered Measurement s Online Design Tools at Pb RoHS Compliant of Low Noise Laser Diode Drivers Optional evaluation boards are available to assist with operating and evaluating any LDD P series module. Figure Top iew Pin Layout and Descriptions TOP IEW LDD P or LDD P LDD P INPUT ANODE CURRENT POWER INPUT CATHODE LD CATHODE LD CATHODE * * * Trimpots shown for proper orientation LDD00P0000A Rev E

2 CURRENT POWER ULATION INPUT C urrent L imit A ttenuator Circuit Current Soft Start Circuit Enable / Disable Circuit P ower S upply Monitor Trip ON/OFF Circuit ANODE LD CATHODE BLOCK DIAGRAM External Connections For LDD P or LDD P (Type A/B Laser Diodes PAGE oltmeter.00 Signal Generator Ω kω. olt Bandgap R eference Laser Limit C urrent A djust T rimpot 0 MΩ Current Adjust Trimpot P: kω P: 0 kω olt Transzorb Surge Protector Photodiode Photodiode Current Laser Diode C urrent Sourc e 00 units :. Ω 00 units :. Ω Laser Diode Forward Current * * DO NOT CONNE CT PIN TO CUR R E NT AND PHOTO SIMULTANEOUSLY Connect for Constant Current Mode Connect for Constant Power Mode Laser Diode LDD P or LDD P Σ Σ Type A Laser Diode Type B Laser Diode Short Laser Diode Anode to Photodiode Cathode Laser Diode Anode & Common Photodiode Cathode Common Cathode Isolated Photodiode LDD00P0000A Rev E

3 CATHODE LD C ATHODE LD A NODE BLOCK DIAGRAM External Connections For LDD P (Type C Laser Diodes PAGE U:A U:B 0 kω 0 kω 0 kω 0 kω U:Analog Devices AD0 Level S hift Circuit C onverts s ignal to reference (Pin 0 MΩ oltmeter.00 CURRENT kω * Signal Generator POWER Level S hift Circuit Converts signal to reference G ND (Pin UL A TION INPUT G ND. olt Bandgap R eference Laser L imit Current Adjust Trimpot Current Adjust Trimpot C urrent L imit A ttenuator Circuit P ower S upply Monitor Trip ON/OFF Circuit C urrent Soft Start Circuit Enable / Disable Circuit olt Transzorb Surge Protector L aser Diode C urrent Sourc e 00 units :. Ω 00 units :. Ω Current Laser Diode Forward Current * DO NOT CONNE CT PIN TO CUR R E NT AND PHOTO SIMULTANEOUSLY Ω Connect for Constant Current Mode kω Connect for Constant Power Mode Photodiode Photodiode Laser Diode Type C Laser Diode Laser Diode Cathode & Photodiode Anode Common Common Anode LDD P Σ Σ LDD00P0000A Rev E

4 ELECTRICAL AND OPERATING SPECIFICATIONS PAGE ABSOLUTE MAXIMUM RATINGS RATING SYMBOL ALUE UNIT Supply oltage (oltage on Pin Current (See SOA Chart Power Dissipation, T AMBIENT C [] Operating Temp case, T AMB C [] Storage Temperature Weight Soldering Temp DD I LD P MAX T OPR T STG to. 00 or 00 or 0 to 0 0 to < 0 C (0 secs olts DC Watts C C oz PARAMETER For Laser Type A or B A or B C EL NUMBER LDD00P LDD00P LDD00P LDD00P LDD00P LDD00P CONSTANT CURRENT CONTROL Temperature Coeffi cient < 00ppm / C < 00ppm / C < 00ppm / C Long Term Stability, hours [] < 0 ppm < 0 ppm < 0 ppm Noise and Ripple (rms [] < μa < μa < μa Current Limit Range Current Monitor Transfer Function 0 / 0 / 0 / 0 / 0 / 0 / CONSTANT POWER CONTROL Photodiode Range 00 μa μa 00 μa Power Stability, hours [] < 0.0% < 0.0% < 0.0% Power Monitor Transfer Function 000 μa/ 0 μa/ 000 μa/ ULATION Input Impedance MΩ MΩ MΩ Depth of Modulation (at 0kHz [] 90% 90% 90% Constant Current Bandwidth, small signal sine wave db up to MHz up to MHz up to MHz Transfer Function [LD] 0 / 0 / 0 / 0 / 0 / 0 / Constant Power Bandwidth, Constant Power [] Depends on Depends on Depends on Transfer Function [] 00 μa / μa / 00 μa / POWER SUPPLY oltage, DD, min oltage, DD, max Current, DD supply, quiescent Power Up Trip Point [] Power Down Trip Point []... Setpoint vs. Monitor Accuracy < % < % < % Warmup to rated accuracy hour hour hour Note []. Maximum Operating Power derates above C. The online Safe Operating Area (SOA Chart includes this derating. Note []. Stability tests were performed in an ambient air environment. Note []. Laser diode forward current noise. Test was performed by measuring the ac voltage across a 0 Ω metal fi lm resistor in series with a laser diode. Note []. As squarewave modulation frequency increases, the peaktopeak output amplitude diminishes. For example, these graphs show the waveform shape at 0 Hz and 0 khz. Depth of modulation continues to decrease after 0 khz. Full Current % 0 0 % 00% Depth of Modulation 90% Depth of Modulation at 0 Hz at 0 khz Note []. Modulation bandwidth in constant power mode depends on photodiode response. Note []. The LDD P series has internal control circuitry which turns the output on and off depending on the voltage at pin. When the voltage reaches the power up trip point, the module soft starts the laser diode. When the voltage reaches the power down trip point, the module shunts current around the laser diode, powering it down in a controlled fashion. 9 % 00 % 90 % LDD00P0000A Rev E

5 PIN DESCRIPTIONS LDD P AND LDD P Pin # Name Function CURRENT POWER INPUT LD CATHODE ANODE Current Monitor (measures Laser Diode current. 0 to. range. Power Monitor (measures Photodiode current. 0 to. range. Inverting modulation input. 0 to range. Power supply and monitor common connection. Laser Diode Cathode. Laser Diode Anode. (Pin internally shorted to pin. Photodiode Anode. Power supply voltage connection. (Pin internally shorted to pin. Supply range: to DC PAGE LDD P Pin # Name Function CURRENT POWER INPUT LD CATHODE CATHODE Current Monitor (measures Laser Diode current. 0 to. range. Power Monitor (measures Photodiode current. 0 to. range. Inverting modulation input. 0 to range. Power supply and monitor common connection. (Pin internally shorted to pin. Laser Diode Anode. Laser Diode Cathode. (Pin internally shorted to pin. Photodiode Cathode. Power supply voltage connection. Supply range: to DC DERING INFMATION LDD EL 00 LASER CURRENT RANGE 00 0 to to 00 PHOTO CURRENT RANGE & LASER PIN CONFIGURATION 0 to 00 A (Type A or B lasers 0 to 00 A (Type C lasers to A (Type A or B lasers P FUNCTIONS P Laser Diode Current Limit & Analog Modulation Input Laser Type A, B, or C A, B or C Evaluation Board and Cable* Model Number LDDPCBP LDDCAB0 Description Evaluation Board 0 cm cable with pin tefl on connector *LDD P sold separately LDD00P0000A Rev E

6 TYPICAL PERFMANCE GRAPHS PAGE Caution: Do not exceed the Safe Operating Area (SOA. Exceeding the SOA voids the warranty. To determine if the operating parameters fall within the SOA of the device, the maximum voltage drop across the driver and the maximum current must be plotted on the SOA curves. These values are used for the example SOA determination: s volts. volts Load I Load 00 } These values are determined from the specifications of the laser diode. Follow these steps:. Determine the maximum voltage drop across the driver, s Load, and mark on the X axis. Example: volts. volts. volts, Point A. Determine the maximum current, I Load, through the driver and mark on the Y axis: (00, Point B. Draw a horizontal line through Point B across the chart. (Line BB. Draw a vertical line from Point A to the maximum current line indicated by Line BB.. Mark S on the X axis. (Point C. Draw the Load Line from where the vertical line from point A intersects Line BB down to Point C. Refer to the chart shown below and note that the Load Line is in the Safe Operating Areas for the LDD00 at C ambient. Note that only Area is safe for the LDD00. Both Areas and are safe for the LDD00. An online tool for calculating your load line is at B BB A C LDD00P0000A Rev E

7 Test Setup for Timing Characteristics and Performance Graphs Switch OPEN CLOSED Off On 0. μf LDD P or LDD P Models CURRENT POWER LASER DR IE R ANODE LD CATHODE TEST LOAD ALL TESTS PERFMED IN CONS TANT CUR R E NT E OPE R ATION S ilicon Diode (N00 S ilicon Diode (N00 Ω PAGE RAIL TO RAIL OUTPUT OPAMP / AD0 Switch OPEN CLOSED 0kΩ 0kΩ Off On 0kΩ 0kΩ CURRENT POWER 0. μf LDD P Models LASER DR IE R CATHODE LD CATHODE LD ANODE TEST LOAD S ilicon Diode (N00 S ilicon Diode (N00 Ω Timing Characteristics Symbol Parameter Test Points Test Conditions * Typical t DELAY Time delay between Power ON Load LDD00P.0 Ω. ms and Laser Diode current start LDD00P.0 Ω. ms LDD00P.0 Ω. ms t RISE Square Wave Response, Load LDD00P.0 Ω 0 nsec 0% to 90% LDD00P.0 Ω 0 nsec LDD00P.0 Ω 0 nsec t FALL Square Wave Response, Load LDD00P.0 Ω 0 nsec 90% to 0% LDD00P.0 Ω 0 nsec LDD00P.0 Ω 0 nsec t SOFT Minimum Load LDD00P.0 Ω 0 msec START (current setpoint 0% full scale LDD00P.0 Ω 0 msec LDD00P.0 Ω 0 msec Maximum Load LDD00P.0 Ω 00 msec (current setpoint 00% full scale LDD00P.0 Ω 00 msec LDD00P.0 Ω 00 msec LDD00P0000A Rev E * LDD00 model results are comparable Note: Keep Operating Setpoint Below Current Limit Setting. These graphs do not represent the LDD P performance while the Current Limit Circuit is triggered. Warning: The Current Limit Circuit is not an absolute/failsafe clamp. If the operating setpoint exceeds the limit setting, and a fast modulation signal is input, very short overshoots of the current limit are possible (0nsec. If the photodiode feedback signal is lost or very slow, the LDD P can drive to its maximum output current.

8 TYPICAL PERFMANCE GRAPHS LDD P & LDD P: WHEN NOT IN CURRENT LIMIT Typical Soft Start Timing (current setpoint at 00% full scale Typical Soft Start Timing (current setpoint at 0% full scale PAGE Horiz Div 00 ms Horiz Div 00 ms Power S upply oltage Power S upply oltage C urrent C urrent Soft start Soft start 0 khz square wave response Large Signal Frequency Response Horiz DIv 0 μsec Modulation Input C urrent Note: Gain normalized to output at 0 Hz. 0 khz square wave rise time 0 khz square wave fall time Horiz DIv 00 nsec Horiz DIv 00 nsec Modulation Input 0 Modulation Input 0 Full Scale 0 C urrent Full Scale 0 C urrent t rise t fall Note: Keep Operating Setpoint Below Current Limit Setting. These graphs do not represent the LDD P performance while the Current Limit Circuit is triggered. Warning: The Current Limit Circuit is not an absolute/failsafe clamp. If the operating setpoint exceeds the limit setting, and a fast modulation signal is input, very short overshoots of the current limit are possible (0nsec. If the photodiode feedback signal is lost or very slow, the LDD P can drive to its maximum output current. LDD00P0000A Rev E

9 TYPICAL PERFMANCE GRAPHS LDD P: WHEN NOT IN CURRENT LIMIT Typical Soft Start Timing (current setpoint at 00% full scale Typical Soft Start Timing (current setpoint at 0% full scale PAGE 9 Horiz Div 00 ms Power S upply oltage Horiz Div 00 ms Power S upply oltage C urrent C urrent Soft start Soft start 0 khz square wave response Large Signal Frequency Response Horiz DIv 0 μsec Modulation Input C urrent Note: Gain normalized to output at 0 Hz. 0 khz square wave rise time Horiz DIv 00 nsec 0 khz square wave fall time Horiz DIv 00 nsec 0 Modulation Input Modulation Input Full Scale C urrent 0 Full Scale C urrent 0 t rise 0 t fall Note: Keep Operating Setpoint Below Current Limit Setting. These graphs do not represent the LDD P performance while the Current Limit Circuit is triggered. Warning: The Current Limit Circuit is not an absolute/failsafe clamp. If the operating setpoint exceeds the limit setting, and a fast modulation signal is input, very short overshoots of the current limit are possible (0 nsec. If the photodiode feedback signal is lost or very slow, the LDD P can drive to its maximum output current. LDD00P0000A Rev E

10 OPERATION POWER SUPPLY AND NOISE PAGE 0 The Laser Diode Drivers are designed for stable, low noise operation. The power supply you select will directly affect the noise performance of the driver. We recommend using a regulated, linear supply for optimum performance. Depending on your requirements, you may be able to use a switching power supply. Each case must be evaluated independently because a switching power supply will affect noise, transient, and stability performance. The LDD P series can be purchased with the LDDPCB series evaluation kit for easy initial operation. LASER SAFETY ISSUES ATTENTION: If you plan to operate the LDD P with any Wavelength temperature controller, you may need to use separate power supplies. If the TE cooler or thermistor is connected to the laser diode, please contact the factory for technical assistance. ATTENTION: Exceeding the maximum specifi ed operating current (IOP MAX will damage your laser diode. Become familiar with the LDD P series module operation and the exact specifications of your laser diode before attaching it to the LDD P module. Seek assistance from someone with experience working with laser diodes if you have not operated one before. ATTENTION: The following instruments may cause momentary opens, shorts, or impedance changes that will damage a laser diode if attached to the output of a laser diode driver.. A voltmeter across the laser diode.. An oscilloscope across the laser diode.. A current meter in series with the laser diode. All measurements made with these instruments on the output should be made with a simulated load attached and not a laser diode. ATTENTION: IF LASER AND PHOTO ARE ISOLATED (TYPE B LASER Short the laser diode anode to the photodiode cathode. The LDD P series laser diode drivers require the photodiode be connected to the laser diode. If no connection is made between the laser diode and the photodiode, then the LDD P will not operate properly in constant power mode, and the power monitor will not read the proper photodiode current. GROUNDING Some laser diode packages short either the laser diode anode or cathode to the case, which may connect the laser electrically to earth ground. Review the internal connections of the LDD P to make sure ground loops are not inadvertantly created by this situation. Special attention to the details of grounding will assure safe operation. DC POWER SUPPLY Earth Ground on USA AC wall socket EARTH Common or Instrument Ground Unless Earth and Instrument Ground are connected via the power supply, Instrument Ground is floating with respect to Earth Ground LDD00P0000A Rev E

11 OPERATING GUIDE GANIZATION PAGE Operating your LDD P series laser diode driver is relatively simple. First, complete basic calculations about your laser diode. Then determine if you ll operate in Constant Power or Constant Current mode. Then following the wiring and operating instructions for that mode. If you re using an evaluation board, familiarize yourself with the components of the board then follow the regular steps. To minimize the possibility of damage to your laser diode, follow these steps in order. Using the LDD P series evalution board? See Setup on page. Step : Calculate safe operating parameters for your laser diode (page (Produce optimum light output power stability Constant Power Mode Select Mode of Operation Constant Current Mode (Produce optimum wavelength stability Step : Wire LDD P for Constant Power Mode (page Step : Confi gure LDD P for Constant Current Mode (page Step : Constant Power Mode Operating Instructions (page Step : Constant Current Mode Operating Instructions (page LDD00P0000A Rev E

12 Step : PreSetup Calculations. Determine Maximum Laser Diode Operating Current ( Using the laser diode manufacturer s recommended operating specifications, determine the following four values: (a Maximum laser diode light output power: P MAX mw (Note this value should be less than the laser diode s ABSOLUTE MAXIMUM RATINGS (b Typical Laser Diode threshold current: I TH (c Typical Laser Diode operating current: I OP (d Laser Diode slope effi ciency: η mw / ( Calculate the laser diode limit current using Equation.: Example Calculations PAGE Laser Diode Optical and Electrical Specifi cations used in this example are found on page. Assume this laser diode application requires the laser diode to produce mw of light output power and uses an LDD00P operating from. [P OP mw & SUPPLY ] P MAX. mw (P MAX is conservatively estimated at 0% of P OP, not the ABSOLUTE MAXIMUM RATING I TH 0 I OP 0 η 0. mw / EQUATION.: I LIMIT I TH (P MAX / (η : If the laser diode s slope effi ciency is unknown, then choose the laser diode limit current to be close to the operating current. Keep it well below the damage threshold of the laser diode. I LIMIT (. * I OP I LIMIT EQUATION.: I LIMIT I TH (P MAX / (η 0 (. / (0... Determine Laser Diode Operating Current for desired Power ( Determine the following: (a Desired laser diode light output power: P OP mw P OP mw ( Calculate the laser diode operating current using Equation. [for I TH & η, see Step.]: EQUATION.: I OP I TH (P OP / (η : If the laser diode s slope effi ciency is unknown, then assume the laser diode operating current is: I OP Laser Diode Current at Rated Power. Determine Laser Diode Monitor Current (Photodiode Current ( Determine the following two values: I OP EQUATION.: I OP I TH (P OP / (η 0 ( / (0.. (a Laser Diode Rated Power: P RATED mw (b Typical Monitor Current (Photodiode current: I MON ( Calculate the laser diode monitor current using Equation. [for P OP see Step.]: P RATED 0 mw I MON 0. [From specifi cation sheet, I MON typical at P O ] EQUATION.: I EQUATION.: I (P OP ( MON I P RATED I I (P OP MON ( ((0. / 0 0. LDD00P0000A Rev E P RATED

13 Step : PreSetup Calculations, continued. Determine Laser Diode Operating oltage (optional ( Using the laser diode manufacturer s recommended operating specifi cations, determine the following four values: (a Typical Laser Diode operating voltage: OP Example Calculations OP. PAGE (b Maximum Laser Diode operating voltage: MAX MAX.0 (c Typical Laser Diode operating current: I OP I OP 0 (d Maximum Laser Diode operating current: I MAX I MAX 0 ( Calculate the laser diode forward voltage drop using Equation. [for I LIMIT see Step.]: EQUATION.: LD OP (I LIMIT I OP If not enough data is available, assume LD. ( MAX OP I MAX I OP LD EQUATION.: LD OP (I LIMIT I OP LD. (0. 0 LD. ( MAX OP I MAX I OP ( Determine R D,alue for Dominant Resistor Protection (optional Resistor R D is not required for proper operation of the LDD P series Laser Diode Driver, but provides a very simple and inexpensive method for protecting the laser diode against various electrical and mechanical transients. ( Determine the following: (a Power Supply oltage applied between pin & pin ( & : SUPPLY SUPPLY ( Calculate R D using I LIMIT from Step., LD from Step., and Equation.. [Note: use Equation.A for LDD 00 models and Equation.B for LDD 00 models]: EQUATION.A: Use with LDD00P, LDD00P, and LDD00P laser diode drivers R D. Ω EQUATION.B: Use with LDD00P, LDD00P, and LDD00P laser diode drivers R D ( SUPPLY LD 0. I LIMIT ( SUPPLY LD 0. I LIMIT. Ω R D Ω EQUATION.A: R D ( SUPPLY LD 0. I LIMIT. 0. ( Ω. Ω Ω ( Calculate the minimum power rating for R D with Equation.: EQUATION.: P RD Minimum power rating for R D (R D (I LIMIT P RD W EQUATION.: P RD (R D (I LIMIT (( W LDD00P0000A Rev E

14 Step : PreSetup Calculations, continued EXAMPLE Laser Diode Electrical and Optical Characteristics ABSOLUTE MAXIMUM RATINGS Symbol Parameter P O Laser Diode Light Power RL Laser Diode Reverse oltage RD Photodiode Reverse oltage Photodiode Forward Current I Ratings 0 0 Units mw PAGE ELECTRICAL / OPTICAL CHARACTERISTICS Symbol I TH I OP η OP I MON Parameter Threshold Current Operating Current Slope Efficiency Operating oltage Monitor Current (photodiode Test Conditions CW CW, P O 0 mw CW, P O 0 mw CW, P O 0 mw CW, P O 0 mw, RD Min.0 Limits Typical Max Units mw / Step : Constant Power Operation: Wiring Figure : LDD P or LDD P Switch OPEN CLOSED Off On OLTMETER This capacitor debounces mechanical switches connected to the input. LDD P or LDD P Models LASER DR IE R CURRENT POWER 0. μf ANODE LD CATHODE WIRE LASER AND PHOTO PHOTO LASER R D LASER Adding R esistor "R D" protects against conditions that could cause damage to the laser diode. This resistor is recommended for operation, but not required. R D PHOTO Figure : LDD P Switch OPEN CLOSED Off On OLTMETER This capacitor debounces mechanical switches connected to the input. LDD P Models LASER DR IE R CURRENT POWER 0. μf CATHODE LD CATHODE LD ANODE WIRE LASER AND PHOTO PHOTO LASER R D LASER Adding R esistor "R D" protects against conditions that could cause damage to the laser diode. This resistor is recommended for operation, but not required. R D PHOTO Figure Figure LDD P AND LDD P E LS LDD P ELS Using a Constant Power Simulated load ANODE LD CATHODE 0. μf or larger N00 N00 Ω N90 CATHODE LD CATHODE 0. μf or larger N00 N00 Ω N90 Figures and illustrate how to create constant power simulated loads for the Type A and Type C laser diodes, respectively. The simulated load allows the confi guration of the LDD P laser diode driver without initially connecting a laser diode. Once the laser diode driver is adjusted to the correct output power and laser diode limit current, power it down before connecting a laser diode. LDD00P0000A Rev E

15 Step : Constant Power Operation PAGE CAUTION: Do not power on the LDD P series Laser Diode Driver until all wire connections are completely attached and the Current Adjust and Limit Current Adjust trimpots have been correctly confi gured. CAUTION: Before connecting a power supply to the LDD P series Laser Diode Driver, measure the supply s output voltage and insure a reading between and olts. Turn OFF the power supply before connecting to the LDD P.. Locate and Adjust onboard trimpots OUTPUT CURRENT ADJUST LASER LIMIT CURRENT ADJUST ( Adjust the OUTPUT CURRENT ADJUST TRIMPOT fully clockwise, at least complete turns. ( Adjust the LIMIT CURRENT ADJUST TRIMPOT fully counterclockwise, at least complete turns. OLTMETER CURRENT POWER. Measure Laser Current Monitor ( Attach the positive input of a voltmeter to the current monitor output (pin and the negative input of the voltmeter to ground (pin. to olts } PHOTO CONNECTION LASER CONNE CTIONS. Turn on oltage Source ( Apply power to the LDD P only after all connections have been thoroughly reviewed. Notice the modulation input, pin, must be connected to ground, pin, to properly confi gure the limit current and photodiode current settings. I LIMIT (from Step.. Adjust Laser Diode Limit Current 00 models: (. PIN (I LIMIT 00 ( 00 models:. PIN (I LIMIT 00 ( Calculate the current monitor voltage that corresponds to the proper limit current setting (determined in Step.. OLTMETER SLOWLY LASER LIMIT CURRENT ADJUST CURRENT POWER ( SLOWLY adjust the LIMIT CURRENT ADJUST TRIMPOT clockwise until the voltmeter attached to the current monitor (pin reads LIMIT. OLTMETER. Measure Power Monitor CURRENT POWER ( Attach the positive input of a voltmeter to the power monitor output (pin, and the negative input of a voltmeter to ground, (pin. LDD00P0000A Rev E

16 Step : Constant Power Operation, continued OUTPUT CURRENT ADJUST I (from Step.. Adjust Photodiode Current (light output power PAGE ( Rotate the OUTPUT CURRENT ADJUST TRIMPOT full counter clockwise, at least turns. LDD P and LDD P models: ( PIN (I.. LDD P models: PIN (I. 0. ( ( Calculate the power monitor voltage that corresponds to the proper photodiode current setting (determined in Step.. SLOWLY OUTPUT CURRENT ADJUST OLTMETER CURRENT POWER ( SLOWLY adjust the OUTPUT CURRENT ADJUST TRIMPOT clockwise until the voltmeter attached to the power monitor (pin reads. I OP (from Step. 00 models: PIN (I OP. 00 A 00 models: PIN (I OP. 00 A OLTMETER ( ( CURRENT POWER.. erify Laser Diode Current level at Current Monitor ( Determine that the laser diode current measured on the current monitor output corresponds to the value calculated in Step.. This value may vary from the calculated value depending on the temperature of the laser diode. A laser diode with a temperature above C will require more laser diode current to produce the same power than if its temperature were C. ( Confi rm that the laser diode current is below the limit current setting. CAUTION: If the current monitor indicates that the laser diode is operating in current limit, reduce the laser diode output power using the OUTPUT CURRENT ADJUST TRIMPOT. Turn the power supply OFF and verify calculations made in Step. Also inspect the laser diode mounting to insure proper heatsinking for the laser diode. Switch OPEN CLOSED Off On CURRENT POWER 0. μf This capacitor debounces mechanical switches connected to the input. ANODE LD CATHODE. Disable Laser Diode Current ( To disable current, let pin fl oat or connect it to. As shown in the diagram, open the switch. NOTE: a residual current is present in the laser diode when disabled. DO NOT DISCONNECT THE LASER UNLESS POWER IS REMOED FROM AND GROUND. LDD00P0000A Rev E

17 Step : Constant Power Operation, continued Bandgap oltage Reference External Trimpot (pin CURRENT POWER.9 Adjust Light Power using the Modulation Input (optional PAGE ( An external trimpot or potentiometer can be attached to pin to remotely control the light output power. Signal Generator Ground CURRENT POWER Connect a signal generator to pin. I (from Step. LDD P and LDD P models: I (I. PIN A ( LDD P models: 0. I (I PIN ( A Step : Constant Current Operation: Wiring Figure : LDD P or LDD P ( The modulation input adjusts the light output power by reducing the photodiode current from the setting determined by the OUTPUT CURRENT ADJUST TRIMPOT proportional to the voltage applied to pin. CAUTION: The modulation input voltage must always be maintained within the power supply voltage range between pin & pin. A voltage on the modulation input below ground may produce excessive laser diode currents. LDD P or LDD P Models OLTMETER LASER DR IE R Switch OPEN CLOSED Off On This capacitor debounces mechanical switches connected to the input. 0. μf CURRENT POWER ANODE LD CATHODE LASER R D Adding R esistor "R D" protects against conditions that could cause damage to the laser diode. This resistor is recommended for operation, but not required. OPTIONAL PHOTO CONNECTION SENSE R SENSE R I I For LDD P, s elect R kω For LDD P, s elect R 0 kω Figure : LDD P Switch OPEN CLOSED Off On RAIL TO RAIL OUTPUT OPAMP / AD0 0kΩ 0kΩ LASER DR IE R 0kΩ CURRENT 0kΩ POWER CATHODE LD 0. μf CATHODE LD ANODE OLT ME TE R This capacitor debounces mechanical switches connected to the input. LDD P Models LASER R D OPTIONAL PHOTO CONNE CTION SENSE R I SENSE R I For LDD P, s elect R kω Adding Resistor "R D" protects against conditions that could cause damage to the laser diode. This resistor is recommended for operation, but not required. LDD00P0000A Rev E

18 Step : Constant Current Operation: Wiring, continued Figure Figure LDD P AND LDD P E LS ANODE LD CATHODE TO PIN N00 N00 LDD P ELS CATHODE LD CATHODE N00 N00 Ω Ω TO R ailtorail Opamp Using a Constant Current Simulated load PAGE Figures and illustrate how to create constant current simulated loads for the LDD P, LDD P, or LDD P laser diode drivers, respectively. The simulated load allows the configuration of the LDD P laser diode driver without initially connecting the laser diode. Once the laser diode driver is adjusted to the correct output current and laser diode limit current, power it down before connecting a laser diode. Step : Constant Current Operation CAUTION: Do not power on the LDD P series Laser Diode Driver until all wire connections are completely attached and the Current Adjust and Limit Current Adjust trimpots have been correctly confi gured. CAUTION: Before connecting a power supply to the LDD P series Laser Diode Driver, measure the supply s output voltage and insure a reading between and olts. Turn OFF the power supply before connecting to the LDD P.. Locate and Adjust onboard trimpots OUTPUT CURRENT ADJUST LASER LIMIT CURRENT ADJUST ( Adjust the OUTPUT CURRENT ADJUST TRIMPOT fully clockwise, at least complete turns. ( Adjust the LIMIT CURRENT ADJUST TRIMPOT fully counterclockwise, at least complete turns. OLTMETER CURRENT POWER. Measure Power Monitor The current monitor and the power monitor outputs produce the same voltage output when the LDD P is confi gured for Constant Current Operation. Since the current monitor is used to provide feedback in constant current mode, the power monitor is used to measure the laser diode current. ( Attach the positive input of a voltmeter to the power monitor output (pin and the negative input of the voltmeter to ground (pin. to ol. Turn on oltage Source } PHO CON LAS CON ( Apply power to the LDD P only after all connections have been thoroughly reviewed. Notice the modulation input, pin, must be connected to ground, pin, to properly configure the limit current and laser diode current settings. LDD00P0000A Rev E

19 Step : Constant Current Operation, continued I LIMIT (from Step. 00 models:. PIN (I LIMIT ( models:. PIN (I LIMIT 00 (. Adjust Laser Diode Limit Current PAGE 9 ( Calculate the current monitor voltage that corresponds to the proper limit current setting (determined in Step.. OLTMETER SLOWLY LASER LIMIT CURRENT ADJUST CURRENT POWER ( SLOWLY adjust the LIMIT CURRENT ADJUST TRIMPOT clockwise until the voltmeter attached to the power monitor (pin reads LIMIT. OUTPUT CURRENT ADJUST. Adjust Laser Diode Current ( Rotate the OUTPUT CURRENT ADJUST TRIMPOT fully counterclockwise, at least turns. I OP (from Step. 00 models: PIN (I OP. 00 ( 00 models: PIN (I OP. 00 ( ( Calculate the current monitor voltage that corresponds to the proper laser diode current setting (determined in Step.. OLTMETER SLOWLY OUTPUT CURRENT ADJUST CURRENT POWER ( SLOWLY adjust the OUTPUT CURRENT ADJUST TRIMPOT clockwise until the voltmeter attached to the current monitor (pin reads OP. Switch OPEN CLOSED Off On CURRENT POWER 0. μf This capacitor debounces mechanical switches connected to the input. ANODE LD CATHODE. Disable Laser Diode Current ( To disable current, let pin fl oat or connect it to. As shown in the diagram, open the switch. NOTE: a residual current is present in the laser diode when disabled. DO NOT DISCONNECT THE LASER UNLESS POWER IS REMOED FROM AND GROUND. LDD00P0000A Rev E

20 Step : Constant Current Operation, continued LDD P and LDD P models OLT ME TE R LASER. erify Photodiode Current level (optional PAGE 0 ( If you wired an external photodiode in Step, attach the leads of a voltmeter across the external resistor as shown. EXT R I EXT R I OLT ME TE R LDD P models EXT R I EXT R I I (from Step. LDD P and LDD P models: ( EXT I kω LDD P models: LASER ( EXT I 0 kω ( Determine if the measured photodiode current corresponds to the value calculated in Step.. This value may vary from the calculated value depending on the temperature of the laser diode. A laser diode with a temperature above C will produce less photodiode current than if its temperature were C. ( Confi rm that the light output power does not exceed the rated output power for the laser diode. CAUTION: If the photodiode current indicates that the laser diode is operating above the rated power, reduce the laser diode output power using the OUTPUT CURRENT ADJUST TRIMPOT. Turn the power supply OFF and verify calculations made in Step. Also inspect the laser diode mounting to insure proper heatsinking for the laser diode. Bandgap oltage Reference External Trimpot (pin CURRENT POWER. Adjust Laser Diode Current using the Modulation Input (optional ( An external trimpot or potentiometer can be attached to pin to remotely control the laser diode current. Signal Generator Ground CURRENT POWER Connect a signal generator to pin. 00 models: I OP (from Step. I (I OP 00 PIN 00 models: ( ( I (I OP PIN 00 ( The modulation input adjusts the laser diode current by reducing the laser diode current from the setting determined by the OUTPUT CURRENT ADJUST TRIMPOT proportional to the voltage applied to pin. CAUTION: The modulation input voltage must always be maintained within the power supply voltage range between pin & pin. A voltage on the modulation input below ground may produce excessive laser diode currents. LDD00P0000A Rev E

21 Using the LDD Evaluation Board PAGE The LDD P is designed to be soldered to a circuit board. The LDDPCB evaluation board integrates with any LDD P laser diode driver. Instructions for using the LDDPCB are on the next four pages. Once you are familiar with the board, follow the operating instructions for the LDD P, starting on page. Model LDDPCB P Series: Component Diagram For more detail refer to sections on the following pages. } } a c b TOP IEW } 9 P/P P } 0 d No. a b c d 9 0 Component LDD Module Enable/ Disable wire pads Jumpers Decoupling Resistor Decoupling Capacitor Transzorb Dominant Impedance LED and bias resistor Measurement wire pads INPUT wire pads Laser diode wire pads External photodiode wire pads Opamp, resistors, one capacitor Power supply wire pads Typical Component Functions Function Laser Diode Driver Component location Enable / Disable laser current Select LDD P model and operating mode Decouple power supply Decouple power supply Overvoltage protection Laser diode overcurrent and transient protection Power ON indicator Measure laser diode or photodiode current Connections to optional signal generator Solder laser diode cable to these pads Monitor photodiode current while in constant laser diode current mode For operating LDD P in constant current mode Connections to power supply Component #: Solder LDD P module to accessory board ( The silkscreen on the top of the board shows the orientation of the two trimpots when the LDD P module is properly positioned. Solder the LDD P to the circuit board. Do not exceed solder tip temperature of 0 C or apply heat to any lead for more than 0 seconds. LDD00P0000A Rev E

22 Using the LDD Evaluation Board, continued Switch OPEN CLOSED Off On 0. μf Component #: Enable laser diode current ( Solder a jumper between the two round solder pads PAGE ( Use a switch to enable and disable the laser diode current. Connect it across the round solder pads. Place a capacitor across the switch to debounce the connection. Use one of these four jumper diagrams to c onfigure the L DDP C B to the model LDD P you are using and the appropriate mode of operation Component #: Configure for LDD P / LDD P or LDD P models & Mode of operation P or P Constant Current P Constant Current ( The top two jumpers configure the evaluation board for the model of LDD P. P or P Constant Power P Constant Power ( The second set of jumpers determine the operating mode Constant Light Power, or Constant Laser Diode Current. P or P Do not ins tall this jumper if operating in Constant Power mode P ( A second set of jumpers, lower on the LDDPCB are used only if you operate in Constant Current mode. CAUTION: Do not load this jumper when operating in Constant Power Mode. Component #: Determine which safety components to install ANODE LD CATHODE a LASER d c R D b Component #a: Power Supply Decoupling Resistor A to 0 ohm resistor can be used to decouple the power supply from the LDD P laser diode driver. This series resistor forms a low pass single pole fi lter with the capacitance seen from pin to ground. This component is not recommended for operation below. A one ohm resistor is installed on the LDDPCB. If you do not install the decoupling resistor, install a jumper between the two solder pads. Component #b: Power Supply Decoupling Capacitor A to 0 μf tantalum or low ESR electrolytic capacitor can be used to shunt regulate the power supply around the LDD P laser diode driver. Note the polarity marked on the silkscreen. A 0 μf capacitor is installed on the LDDPCB. Component #c: Overvoltage protection Transzorb This zener diode limits the voltage differential across the LDD P. A typical transzorb for a supply would be the Motorola PKEA. Solder the cathode of the transzorb in the square solder pad. A PKEA is installed on the LDDPCB. Component #d: Dominant Impedance This resistor limits the voltage that can develop across the laser diode in the case of a power supply transient or if the connections to the laser diode are broken and reconnected. Select either a metal fi lm power resistor or a noninductive wire wound resistor. Carbon based resistors add a signifi cant amount of noise and inductive wire wound resistors can damage the laser diode. If you do not install the dominant impedance resistor, install a jumper between the two solder pads. A value for R D is calculated in Step. of the operating instructions (starting on page. A 0 Ω, W resistor is installed on the LDDPCB. LDD00P0000A Rev E

23 Using the LDD Evaluation Board, continued anode cathode Component #: Power ON indicator LED (optional When power is applied to the LDD P evaluation board, this LED will light. A kω resistor in series with the LED establishes a bias current A kω resistor and a green indicator LED are installed on the LDDPCB. PAGE OLTMETER Component #: Connect oltmeter to monitor laser diode power or current INPUT (PIN Power S upply Connections Pin (current monitor and pin (power monitor are used to monitor laser diode current and power during setup and operation. These pins are brought out to solder pads on the edge of the accessory board. POWER (PIN CURRENT (PIN } GROUND (PIN ( Attach the positive input of a voltmeter to either solder pad and the negative input of the voltmeter to ground. NOTE: For noise reduction, use the Monitor Ground solder pad, not the Power Supply ground solder pad. OLTMETER Component #: Connect signal generator to INPUT (optional INPUT (PIN POWER (PIN CURRENT (PIN POWER GROUND (PIN GROUND (PIN Pin is a modulation input. This pin is brought out to a solder pad on the edge of the board. ( Attach the positive input of a signal generator to the far left solder pad and the negative input of the signal generator to the monitor ground. Component #: Connect Laser Diode to accessory board PHOTO CONNECTION LASER CONNE CTIONS { These three pins correspond to pins,, and of the LDD P module. Refer to Step for Wiring Instructions for Constant Power mode (page. Refer to Step for Wiring Instructions for Constant Current mode (page. If you are operating in constant laser diode current mode and want to monitor the photodiode current, the next section details how to wire the photodiode. LDD P and LDD P Component #9: Monitor Photodiode Current in Constant Laser Diode Current Mode Anode LD Anode LD Cathode Sense Resistor Sense Sense Photodiode (a If you are operating an LDD P or LDD P laser diode driver, connect the anode of the photodiode to pin. Connect the photodiode cathode to the laser diode (in most laser diodes, this connection is made inside the laser diode case. (b If you are operating an LDD P laser diode driver, connect the cathode of the photodiode to pin. The photodiode anode should already be connected to the laser diode inside the laser diode case. Cathode LD Cathode LD Anode Sense Resistor LDD P Sense Sense Photodiode ( Install the sense resistor across the two wire pads indicated in the diagram. Use a kω resistor for the LDD P and LDD P models. Use a 0 kω resistor for the LDD P models. ( During operation, monitor the voltage across the Sense and Sense solder pads with a voltmeter. Two resistors are included (loose in the LDDPCB package. One is kω and the other is 0 kω. LDD00P0000A Rev E

24 Using the LDD Evaluation Board, continued 0 k Ω resistors ( railtorail opamp (AD0 0. μf capacitor Component #0: LDD P in Constant Laser Diode Current Operation To operate an LDD P in constant laser diode current mode, an external opamp and components are required. These are installed on the LDDPCB. PAGE OLTMETER INPUT (PIN POWER (PIN CURRENT (PIN POWER GROUND (PIN GROUND (PIN Component #: Connect Power Supply ( Connect and Ground to the solder pads indicated. NOTE: To minimize noise, use the Power Ground solder pad, not the Monitor Ground solder pad. To complete setup, follow the operating instructions starting on page. LDD00P0000A Rev E

25 Application Notes External Trimpot Circuit ( kω (metal film CCW Bandgap Rpot μf* oltage INPUT ( Reference CW ( R pot 0k to 00 kω * Add capacitor to reduce noise Change the Modulation Transfer Function IN R R INPUT ( ( PAGE Laser Diode Protection when using a long cable With a cable longer than two feet, add a Schottky diode across the laser diode. LD Anode LD Cathode Filter the LDD P If you are not modulating the laser diode, add capacitors to reduce the noise by fi ltering the output current. LD Anode LD Cathode Cable > feet 0 μf Tantalum S chottky Diode (N 0. μf S chottky Diode (N Laser Diode Laser Diode New Transfer Function K eep R and R below 00 kω for maximum accuracy. R ( R R Example: (for LDD00P, Constant Current Mode New Transfer Function 9 ( ( 9 Change LDD P Photodiode Range Put a resistor across pins ( and ( to modify the range. 0 kω Original Trans fer Functio R kω R 9 kω 0 / Maximum (. (R (0000 Photodiode [Amps ] R 0 kω R 0 kω R 0000 Current Switch OPEN CLOSED Using the LDD P and LDD P with a Negative Power Supply to earth ground the laser diode anode 0. μf Off On LASER DR IE R CURRENT POWER ANODE LD CATHODE OUTPUT CURRENT ADJUS T LASER LIMIT CURRENT ADJUST R LD Convert Current Monitor to m / m / R total R fixed R trim m / μa Convert Power Monitor to m / A (LDD P only / LM or LMC W W Opamp can be / of: National S emiconductor LM or Analog Devices AD0 R fixed CCW R trim CW R fixed CCW R trim CW LDD00 9 Ω 0 Ω 00 Ω R total R fixed R trim 0 kω R total LDD P 0 kω R total Ω Ω 00 Ω TO PIN (CURRENT TO PIN ( LDD00 90 Ω 0 Ω 00 Ω All resistors are metal fi lm All resistors are metal fi lm TO PIN (POWE R TO PIN ( To use a TTL signal at the INPUT TTL signals require preconditioning. The following circuit fi lters the TTL signal appropriately (low pass with a corner frequency of khz. Note: With applied at the INPUT, a residual output current will still fl ow through the laser diode. IN 00 Ω 0. μf INP UT ( ( LDD00P0000A Rev E

26 MECHANICAL SPECIFICATIONS Laser Diode Driver PAGE TOP IEW SIDE IEW PCB PAD PATTERN.0" [.0mm] PAD HOLE 0.0 DIA TYP. WITH 0.00 PAD TRIMPOT ADJUSTS.0" [.0mm] 0.0" [.0mm] 0." [.9mm] 0." [.mm] 0." [.9mm] 0." [.mm] 0." [0.9mm] 0.0" [.mm] 0.0" [.0mm] 0." [.9mm] All Dimensions: Inches [mm] Laser Diode Driver Evaluation Board TOP IEW.0" [0.mm].0" [.0mm] LASER HOOKUP.00" [.mm].00" [0.mm] All Dimensions: Inches [mm] LDD00P0000A Rev E

27 CERTIFICATION AND WARRANTY CERTIFICATION: Wavelength Electronics (Wavelength certifies that this product met it s published specifications at the time of shipment. Wavelength further certifies that its calibration measurements are traceable to the United States National Institute of Standards and Technology, to the extent allowed by that organization s calibration facilities, and to the calibration facilities of other International Standards Organization members. WARRANTY: This Wavelength product is warranted against defects in materials and workmanship for a period of 90 days from date of shipment. During the warranty period, Wavelength will, at its option, either repair or replace products which prove to be defective. PAGE NOTICE: The information contained in this document is subject to change without notice. Wavelength will not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material. No part of this document may be photocopied, reproduced, or translated to another language without the prior written consent of Wavelength. SAFETY: There are no user serviceable parts inside this product. Return the product to Wavelength Electronics for service and repair to ensure that safety features are maintained. WARRANTY SERICE: For warranty service or repair, this product must be returned to the factory. An RMA is required for products returned to Wavelength for warranty service. The Buyer shall prepay shipping charges to Wavelength and Wavelength shall pay shipping charges to return the product to the Buyer upon determination of defective materials or workmanship. However, the Buyer shall pay all shipping charges, duties, and taxes for products returned to Wavelength from another country. LIMITATIONS OF WARRANTY: The warranty shall not apply to defects resulting from improper use or misuse of the product or operation outside published specifications. No other warranty is expressed or implied. Wavelength specifically disclaims the implied warranties of merchantability and fitness for a particular purpose. EXCLUSIE REMEDIES: The remedies provided herein are the Buyer s sole and exclusive remedies. Wavelength shall not be liable for any direct, indirect, special, incidental, or consequential damages, whether based on contract, tort, or any other legal theory. LIFE SUPPT POLICY: As a general policy, Wavelength Electronics, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the Wavelength product can be reasonably expected to cause failure of the life support device or to significantly affect its safety or effectiveness. Wavelength will not knowingly sell its products for use in such applications unless it receives written assurances satisfactory to Wavelength that the risks of injury or damage have been minimized, the customer assumes all such risks, and there is no product liability for Wavelength. Examples of devices considered to be life support devices are neonatal oxygen analyzers, nerve stimulators (for any use, auto transfusion devices, blood pumps, defibrillators, arrhythmia detectors and alarms, pacemakers, hemodialysis systems, peritoneal dialysis systems, ventilators of all types, and infusion pumps as well as other devices designated as critical by the FDA. The above are representative examples only and are not intended to be conclusive or exclusive of any other life support device. REISION RE. D RE. E REISION HISTY DATE Aug0 9Sep09 NOTES Initial release Updated to reflect RoHS compliance WAELENGTH ELECTRONICS, INC. Evergreen Drive Bozeman, Montana, 9 phone: (0 90 Sales and Technical Support fax: (0 9 sales@teamwavelength.com web: LDD00P0000A Rev E