TEC SourceMeter® Autotuning TEC SourceMeter®
Contents
1. Autotuning TEC SourceMeter TEC OUTPUT SPECIFICATIONS The Model 2510 and 2510 AT TEC SourceMeter instruments are designed to Control the power to the TEC to maintain a constant temperature current voltage or thermistor resistance Measure the resistance of the TEC Provide greater control and flexibility through a software P I D loop CONTROL SYSTEM SPECIFICATIONS SET Constant Peltier Temperature Constant Peltier Voltage Constant Peltier Current Constant Thermistor Resistance CONTROL METHOD Programmable software PID loop Proportional Integral and Derivative gains independently programmable SETPOINT SHORT TERM STABILITY 0 005 C rms16 SETPOINT LONG TERM STABILITY 0 01 C68 SETPOINT RANGE 50 C to 225 C UPPER TEMPERATURE LIMIT 250 C max LOWER TEMPERATURE LIMIT 50 C max SETPOINT RESOLUTION 0 001 C lt 400uV lt 200uA 0 01 of nominal 25 C thermistor resis tance HARDWARE CURRENT LIMIT 1 0A to 5 25A 5 SOFTWARE VOLTAGE LIMIT 0 5 to 10 5V 5 OUTPUT RIPPLE lt 5mV rms OUTPUT RANGE 10 VDC at up to 5 ADC AC RESISTANCE EXCITATION 9 6mA 90uA TEC MEASUREMENT SPECIFICATIONS FUNCTION Operating Resistance 19 11 2 Operating Voltage 21 Operating Current AC Resistance 18 AC Resistance 10 18 90 Days 23 C 5 C 1 0 of rdg 0 19 1 Year 23 C 5 C 2 0 of rdg 0 19 0 05 of rdg 2mV 0 1 of rdg 4m2. thermistors RTDs and IC sensors Maintains constant temperature current voltage and sensor resistance AC Ohms measurement function verifies integrity of TEC Measures and displays TEC parameters during the control cycle 4 wire open short lead detection for thermal feedback element IEEE 488 and RS 232 interfaces Compact half rack design 1 888 KEITHLEY u s ony TEC SourceMeter Autotuning TEC SourceMeter very important due to the sensitivi ty of the laser diode to temperature changes If the temperature varies the laser diode s dominant output wavelength may change leading to signal overlap and crosstalk prob lems Autotuning Function The Model 2510 AT Autotuning TEC SourceMeter instrument offers Figure 2 Laser Diode TEC Minimum Overshoot 10 15 Time s Figure 3 Laser Diode TEC Minimum Settling Time 10 15 Time s Figure 4 manufacturers the ability to auto matically tune the temperature control loop required for CW test ing of optoelectronic components such as laser diode modules and thermo optic switches This capability eliminates the need for time consuming experimentation to determine the optimal P I D coefficient values The Model 2510 AT s P I D Auto Tune software employs a modified Ziegler Nichols algorithm to determine the coefficients used to control the P I D loop This algorithm ensures that the final settl
3. 2510 TEC SourceMeter 2510 AT Autotuning TEC SourceMeter The Model 2510 and 2510 AT TEC SourceMeter instruments enhance Keithley s CW test solution for high speed LIV light current voltage testing of laser diode modules These 50W bipolar instru ments were developed in close cooperation with leading manufacturers of laser diode modules for fiberoptic telecommunications networks Designed to ensure tight temperature control for the device KEITHLEY 2510 AT AUTOTUNING TEC SourceMeter under test the Model 2510 was the first in a line of rv O highly specialized instruments created for telecom munications laser diode testing It brings together onncjmenv Ca Y fonos Keithley s expertise in high speed DC sourcing and o i jli a j measurement with the ability to control the opera tion of a laser diode module s Thermo Electric Cooler or TEC sometimes called a Peltier device accurately The Model 2510 AT expands the capability of the Model 2510 further by offering autotuning capabili ty P I and D proportional integral and deriva tive values for closed loop temperature control are determined by the instrument using a modified Zeigler Nichols algorithm This eliminates the need for users to determine the optimal values for these coefficients experimentally In all other respects the Model 2510 and Model 2510 AT provide exactly the 2510 TEC SourceMeter same set of features and capabili
4. in LO lead 18 Resistance range 0Q to 100Q for rated accuracy 19 Accuracy figures represent the uncertainty that the Model 2510 may add to the temperature measurement not including thermistor uncertainty These accuracy figures are for thermistors with typical A B C constants YAU RW N Ka 28775 Aurora Road Cleveland Ohio 44139 440 248 0400 Fax 440 248 6168 No 2215 5023KGW
5. temperature set point range than other lower power solutions A GREATER MEASURE OF CONFIDENCE 2510 2510 AT High Stability P I D Control When compared with other TEC controllers which use less sophisticated P I proportional integral loops and hardware control mechanisms this instru ment s software based fully digital P I D proportional integral derivative con trol provides greater temperature stability and can be easily upgraded with a simple firmware change The resulting temperature stability 0 005 C short term 0 01 C long term allows for very fine control over the output wave length and optical power of the laser diode module during production testing of DC characteristics This improved stability gives users higher confidence in measured values especially for components or sub assemblies in wavelength multiplexed networks The derivative component of the instrument s P I D control also reduces the required waiting time between making measurements at various temperature set points The temperature set point range of 50 C to 225 C covers most of the test requirements for production testing of cooled optical components and sub assemblies with a resolution of 0 001 C Before the introduction of the Model 2510 AT configuring test systems for new module designs and fixtures required the user to determine the best combina tion of P I and D coefficients through trial and error experimentation The Model 2510
6. 3 e www keithley com Copyright 2002 Keithley Instruments Inc Printed in the U S A Current Output 1 13 5V 833 uA Voltage Output V 2 5 mA 15 75V max 100 kQ 33 uA 6 6 V max 0 200 kQ 2 9 50 to 250 C 12 40 to 100 C 2 9 40 to 100 C A B C settable 0 04 212 Slope amp offset 0 03 100 nA Slope amp offset 0 03 500 uV NOTES Model 2510 and device under test in a regulated ambient temperature of an With remote voltage sense 1 year 23 C 5 C With Ipaa 5A and Vicy OV With Isaa 5A and Vioag 10V With 10kQ thermistor as sensor Short term stability is defined as 24 hours with Peltier and Model 2510 at 25 C 0 5 C Long term stability is defined as 30 days with Peltier and Model 2510 at 25 C 0 5 C 10Hz to 10MHz measured at 5A output into a 2Q load 10 Common mode voltage OV meter connect enabled connects Peltier low output to thermistor measure circuit ground 11 Resistance range 0Q to 20Q for rated accuracy 12 Current through Peltier gt 0 2A 13 Default values shown selectable values of 34A 10wA 334A 1004A 833A 2 5mA Note that temperature control performance will degrade at lower currents 14AC Ohms is a dual pulsed measurement using current reversals available over bus only 15 Settable to lt 400uV and lt 200uA in constant V and constant I mode respectively 16 For line frequency 0 1 17 For 1kQ unbalance
7. AT s autotuning function uses the modified Zeigler Nichols algo rithm to determine the optimal P I and D values automatically Adaptable to Evolving DUT Requirements The Model 2510 and Model 2510 AT are well suited for testing a wide range of laser diode modules because they are compatible with the types of tempera ture sensors most commonly used in these modules In addition to 100 1kQ 10kQ and 100kQ thermistors they can handle inputs from 100Q or 1kQ RTDs and a variety of solid state temperature sensors This input flexibili y ensures their adaptability as the modules being tested evolve over time Programmable Set Points and Limits Users can assign temperature current voltage and thermistor resistance set oints The thermistor resistance set point feature allows higher correlation of est results with actual performance in the field for laser diode modules because reference resistors are used to control the temperature of the module Programmable power current and temperature limits offer maximum protec ion against damage to the device under test Accurate Real Time Measurements Both models can perform real time measurements on the TEC including TEC current voltage drop power dissipation and resistance providing valuable information on the operation of the thermal control system Peltier TEC Ohms Measurement TEC devices are easily affected by mechanical damage such as sheer stress dur ing assembly The most ef
8. V 0 2 of rdg 4mA 0 4 of rdg 8mA 0 05 of rdg 0 012 0 10 of rdg 0 02Q 0 1 of rdg 0 1 0 2 of rdg 0 2Q OPEN SHORTED THERMOELECTRIC DETECTION LOAD IMPEDANCE Stable into 1uF typical COMMON MODE VOLTAGE 30VDC maximum COMMON MODE ISOLATION gt 10 Q lt 1500pF MAX VOLTAGE DROP BETWEEN INPUT OUTPUT SENSE TERMINALS 1 volt MAX SENSE LEAD RESISTANCE 1Q for rated accuracy MAX FORCE LEAD RESISTANCE 0 12 SENSE INPUT IMPEDANCE gt 400kQ THERMAL FEEDBACK ELEMENT SPECIFICATIONS 1kQ 833 uA Excitation 2 5 mA 4V max 0 250 Q 0 2 50 kQ 1 5 2 9 50 to 250 C 50 to 250 C Nominal Resistance Range Excitation Accuracy Nominal Sensor Temperature Range Calibration Measurement Accuracy rdg offset a B Ssettable a B 5 settable 0 04 0 07 Q 0 04 0 04 Q THERMISTOR MEASUREMENT ACCURACY Nominal Thermistor Accuracy vs Temperature Resistance 0 C 25 C 50 C 100 C 100 Q 0 021 C 0 035 C 0 070 C 0 27 C 1kQ 0 015 C 0 023 C 0 045 C 0 18 C 10kQ 0 006 C 0 012 C 0 026 C 0 15 C 100 kQ 0 009 C 0 014 C 0 026 C 0 13 C OPEN SHORTED ELEMENT DETECTION SOFTWARE LINEARIZATION FOR THERMISTOR AND RTD COMMON MODE VOLTAGE 30VDC COMMON MODE ISOLATION gt 10 Q lt 1000pF MAX VOLTAGE DROP BETWEEN INPUT OUTPUT SENSE TER MINALS 1 volt MAX SENSE LEAD RESISTANCE 100Q for rated accuracy SENSE INPUT IMPEDANCE gt 1 108Q Specifica
9. fective method to test a device for damage after it has been incorporated into a laser diode module is to perform a low level AC or reversing DC ohms measurement If there is a change in the TEC s resistance value when compared with the manufacturer s specification mechanical dam age is indicated Unlike a standard DC resistance measurement where the cur rent passing through the device can produce device heating and affect the measured resistance the reversing DC ohms method does not and allows more accurate measurements Open Short Lead Detection Both models of the instrument use a four wire measurement method to detect open short leads on the temperature sensor before testing Four wire measurements eliminate lead resistance errors on the measured value reduc ing the possibility of false failures or device damage 1 888 KEITHLEY wis ony www keithley com A GREATER TEC SourceMeter Autotuning TEC SourceMeter Interface Options Like all newer Keithley instruments both models of the instrument include standard IEEE 488 and RS 232 interfaces to speed and simplify system integra tion and control Optional Resistive Heater Adapter The Model 2510 RH Resistive Heater Adapter enables either model of the instrument to provide closed loop tem perature control for resistive heater ele ments rather than for TECs When the adapter is installed at the instrument s output terminal current flows through the re
10. ing perturbations are damped by 25 each cycle of the oscillation The autotuning process begins with applying a voltage step input to the system being tuned in open loop mode and measuring several parameters of the system s response to this voltage step function The system s response to the step function is illustrated in Figure 2 The lag time of the system response the maximum initial slope and the TAU 63 1 e response time are mea sured then used to generate the Kp proportional gain constant Ki integral gain constant and Kd derivative gain constant coefficients The autotuning function offers users a choice of a minimum settling time mode or a minimum over shoot mode which provides the Model 2510 AT with the flexibility to be used with a variety of load types and devices For example when controlling a large area TEC in a test fixture optimized for P I and D values minimum overshoot protects the devices in the fixture from damage Figure 3 For temperature set points that do not approach the maximum specified temperature for the device under test the minimum settling time mode can be used to speed up the autotuning function Figure 4 50W Output As the complexity of today s laser diode modules increases higher power levels are needed in tem perature controllers to address the module s cooling needs during production test The 50W 5A 10V output allows for higher testing speed and a wider
11. sistive heater when the P I D loop indicates heating However no current will flow to the resistive heater when the temperature loop calls for cooling The resistive element is cooled through radiation conduction or convection Trigger Link AK Thermistor Peltier Computer 2500INT Integrating Sphere Figure 5 This graph compares the Model 2510 2510 AT s A D converter resolution and temperature stability with that of a leading competitive instrument While the competitive instrument uses an analog proportional integral P I control loop it displays information in digital format through a low resolution analog to digital converter In contrast the Model 2510 2510 AT uses a high precision digital P I D control loop which pro vides greater temperature stability both over the short term 0 005 C and the long term 0 01 C KENT HLEY MEASURE OF CONFIDENCE for optimal performance a j i _ N oO Ll p _ i t a i o i _ _ D a Ke i se x dm oa OPTOELECTRONIC TEST SOLUTIONS Model 2510 2510 AT Specifications e Z O l e 2 YY W OQ Z e a O W l W O E ou fo 2510 2510 AT SPECIFICATIONS TEC SourceMeter
12. ties 2510 AT Autotuning TEC The SourceMeter Concept SourceMeter The Model 2510 and Model 2510 AT draw upon Keithley s unique SourceMeter concept which combines o S a precision voltage current sourcing and measurement functions into a single instrument SourceMeter These products are available instruments provide numerous advantages over the use of separate instruments including lower acquisi with an Extended Warranty tion and maintenance costs the need for less rack space easier system integration and programming and broad dynamic range Part of a Comprehensive LIV Test System User s Manual Input Output Connector In a laser diode CW test stand the Model 2510 or Model 2510 AT can control the temperature of actively cooled optical components and assemblies such as laser diode modules to within 0 005 C of the user defined set point During testing the instrument measures the internal temperature of the laser diode module from any of a variety of temperature sensors then drives power through the TEC within the laser diode module in order to maintain its temperature at the desired set point Active temperature control is ACCESSORIES AVAILABLE 2510 RH Resistive Heater Adapter for Model 2510 Figure 1 The capabilities of 2510 CAB 4Wire enres Cable Phoenix Connector to the Model 2510 and 2510 Trigger Link Unterminated En AT are intended to comple ment those of other Keithley instrumen
13. tions are subject to change without notice All Keithley trademarks and trade names are the property of Keithley Instruments Inc All other trademarks and trade names are the property of their respective companies KENT HLEY Keithley Instruments Inc 100 Q 2 5 mA 8 V max 0 1 kQ 2 9 50 to 250 C 1kQ 833 uA 8 V max 0 10 kQ 2 9 50 to 250 C 10 kQ 100 uA 8 V max 0 80 kQ 2 9 50 to 250 C A B C settable 0 04 0 07 Q A B C settable 0 04 0 4 Q A B C settable 0 02 32 GENERAL NOISE REJECTION SPEED NPLC Normal 1 00 NMRR 60 dB SOURCE OUTPUT MODES Fixed DC level PROGRAMMABILITY IEEE 488 SCPI 1995 0 RS 232 3 user definable power up states plus factory default and RST POWER SUPPLY 90V to 260V rms 50 60Hz 75W WARRANTY 1 year EMC Complies with European Union Directive 98 336 EEC CE marking requirements FCC part 15 class B CTSPR 11 CMRR 120 dB IEC 801 2 IEC 801 3 IEC 801 4 VIBRATION MIL PRF 28800F Class 3 Random Vibration WARM UP 1 hour to rated accuracies DIMENSIONS WEIGHT 89mm high x 213 mm high x 370mm deep 3 in x 8 in x 14 6 in Bench configu ration with handle amp feet 104mm high x 238mm wide x 370mm deep 4 in x 9 in x 14 s in Net Weight 3 21kg 7 08 lbs ENVIRONMENT Operating 0 50 C 70 R H up to 35 C Derate 3 R H C 35 50 C Storage 25 to 65 C 1 888 KEITHLEY 534 845
14. ts often used in APPLICATIONS laser diode module LIV test Control and production testing of ing including the Model thermoelectric coolers Peltier 2400 and 2420 SourceMeter devices in instruments the Model Thermistor Peltier 2500 Dual Photodiode e Laser diode modules Meter and Model 2500INT Integrating Sphere e IR charge coupled device CCD ee arrays and charge injection devices CID e Cooled photodetectors Computer e Thermal optic switches e Temperature controlled fixtures 1 888 KEITHLEY wis ony KEITHLEY www keithley com A GREATER MEASURE OF CONFIDENCE 2500INT amp 2 i i t Z i N thi i 5 a i o i _ D a ps i ee OPTOELECTRONIC TEST SOLUTIONS e Z O l Oo Y W 9 zZ oO oa O W l Ww 0 E ou Oo 2510 2510 AT 50W TEC Controller combined with DC measurement functions Provides fully digital P I D control 2510 AT provides autotuning capability for the thermal control loop Designed to control temperature during laser diode module testing Wide temperature set point range 50 C to 225 C and high set point resolution 0 001 C and stability 0 005 C Compatible with a variety of temperature sensor inputs
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