TEC SourceMeter 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 instruments 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 under test, the Model 2510 was the first in a line of highly specialized instruments created for telecommunications laser diode testing. It brings together Keithley's expertise in high-speed DC sourcing and measurement with the ability to control the operation of a laser diode module's Thermo-Electric Cooler or TEC (sometimes called a "Peltier device") accurately. Ordering Information 2510 2510-AT TEC SourceMeter Autotuning TEC SourceMeter These products are available with an Extended Warranty. Accessories Supplied User's Manual, Input/Output Connector The Model 2510-AT expands the capability of the Model 2510 further by offering autotuning capability. P, I, and D (proportional, integral, and derivative) 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 same set of features and capabilities. The SourceMeter Concept The Model 2510 and Model 2510-AT draw upon Keithley's unique SourceMeter concept, which combines precision voltage/current sourcing and measurement functions into a single instrument. SourceMeter instruments provide numerous advantages over the use of separate instruments, including lower acquisition 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 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 0.005C of the userdefined 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 2510-CAB Resistive Heater Adapter for Model 2510 4-Wire Unshielded Cable, Phoenix Connector to Unterminated End APPLICATIONS Control and production testing of thermoelectric coolers/Peltier devices in: * Laser diode modules * IR charge-coupled device (CCD) arrays and charge-injection devices (CID) Figure 1. The capabilities of the Model 2510 and 2510AT are intended to complement those of other Keithley instruments often used in laser diode module LIV testing, including the Model 2400 and 2420 SourceMeter instruments, the Model 2500 Dual Photodiode Meter and Model 2500INT Integrating Sphere. Trigger Link 2510 Thermistor Peltier 2400/ 2420 2500 Fiber * Cooled photodetectors GPIB Computer * Thermal-optic switches * Temperature controlled fixtures 2500INT 1.888.KEITHLEY (U.S. only) www.keithley.com A Precision temperature control for TECs with auto tuning PID for optimal performance (R) G R E A T E R M E A S U R E O F C O N F I D E N C E OPTOELECTRONIC TEST SOLUTIONS 2510 2510-AT (R) TEC SourceMeter Autotuning TEC SourceMeter (R) * 50W TEC Controller combined with DC measurement functions * Provides fully digital P-I-D control TMAX Max. Initial Slope * 2510-AT provides autotuning capability for the thermal control loop * Designed to control temperature during laser diode module testing * Wide temperature set point range (-50C to +225C) and high set point resolution (0.001C) and stability (0.005C) * AC Ohms measurement function verifies integrity of TEC 63% TSTART L TS tL te Figure 2. * Compatible with a variety of temperature sensor inputs-- thermistors, RTDs, and IC sensors * Maintains constant temperature, current, voltage, and sensor resistance very important due to the sensitivity 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 problems. Temp Laser Diode TEC Minimum Overshoot 27 26 Temp (C) Precision temperature control for TECs with auto tuning PID for optimal performance 2510 2510-AT (R) 25 24 * Measures and displays TEC parameters during the control cycle 23 0 5 * 4-wire open/short lead detection for thermal feedback element * IEEE-488 and RS-232 interfaces 10 15 20 25 Time (s) Figure 3. * Compact, half-rack design Laser Diode TEC Minimum Settling Time 27 Temp (C) OPTOELECTRONIC TEST SOLUTIONS 26 25 24 23 0 5 10 15 20 25 Autotuning Function The Model 2510-AT Autotuning Time TEC SourceMeter instrument offers manufacturers the ability to automatically tune the temperature control loop required for CW testing 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 settling 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 measured, 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 overshoot 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). Time (s) 50W Output As the complexity of today's laser diode modules increases, higher power levels are needed in temperature controllers to address the module's cooling needs during production test. The 50W (5A@10V) output allows for higher testing speed and a wider temperature set point range than other, lower-power solutions. Figure 4. 1.888.KEITHLEY (U.S. only) www.keithley.com A G R E A T E R M E A S U R E O F C O N F I D E N C E TEC SourceMeter Autotuning TEC SourceMeter 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 instrument's software-based, fully digital P-I-D (proportional-integral-derivative) control provides greater temperature stability and can be easily upgraded with a simple firmware change. The resulting temperature stability (0.005C short term, 0.01C long term) allows for very fine control over the output wavelength 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 -50C to +225C covers most of the test requirements for production testing of cooled optical components and sub-assemblies, with a resolution of 0.001C. Before the introduction of the Model 2510-AT, configuring test systems for new module designs and fixtures required the user to determine the best combination of P, I, and D coefficients through trial-and-error experimentation. The Model 2510-AT's autotuning function uses the modified Zeigler-Nichols algorithm to determine the optimal P, I, and D values automatically. 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 integration and control. Optional Resistive Heater Adapter The Model 2510-RH Resistive Heater Adapter enables either model of the instrument to provide closed loop temperature control for resistive heater elements, rather than for TECs. When the adapter is installed at the instrument's output terminal, current flows through the resistive 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. 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 temperature sensors most commonly used in these modules. In addition to 100, 1k, 10k, and 100k thermistors, they can handle inputs from 100 or 1k RTDs, and a variety of solid-state temperature sensors. This input flexibility 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 points. The thermistor resistance set point feature allows higher correlation of test 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 protection against damage to the device under test. Trigger Link 2510 Thermistor 2400/ 2420 2500 Fiber GPIB Computer 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 during assembly. The most effective 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 damage is indicated. Unlike a standard DC resistance measurement, where the current 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. Peltier 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 proportionalintegral (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 provides greater temperature stability, both over the short term (0.005C) and the long term ( 0.01C). 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, reducing the possibility of false failures or device damage. 1.888.KEITHLEY (U.S. only) www.keithley.com A G R E A T E R M E A S U R E O F C O N F I D E N C E Precision temperature control for TECs with auto tuning PID for optimal performance (R) OPTOELECTRONIC TEST SOLUTIONS 2510 2510-AT (R) (R) TEC SourceMeter Autotuning TEC SourceMeter 2510 2510-AT (R) 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. Model 2510, 2510-AT Specifications 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: 0.005C rms1,6,7. SETPOINT LONG TERM STABILITY: 0.01C1,6,8. SETPOINT RANGE: -50C to 225C. UPPER TEMPERATURE LIMIT: 250C max. LOWER TEMPERATURE LIMIT: -50C max. SETPOINT RESOLUTION: 0.001C, <400V, <200A 0.01% of nominal (25C) thermistor resistance. HARDWARE CURRENT LIMIT: 1.0A to 5.25A 5%. SOFTWARE VOLTAGE LIMIT:0.5 to 10.5V 5%. OUTPUT RANGE: 10 VDC at up to 5 ADC.15 OUTPUT RIPPLE: <5mV rms9. AC RESISTANCE EXCITATION: (9.6mA 90A).14 TEC MEASUREMENT SPECIFICATIONS3 FUNCTION Operating Resistance 2, 10, 11, 12 Operating Voltage 2,10 Operating Current10 AC Resistance 2, 18 AC Resistance 2, 10, 18 90 Days, 23C 5C (1.0% of rdg + 0.1) (0.05% of rdg + 2mV) (0.2% of rdg + 4mA) (0.05% of rdg + 0.01) (0.1% of rdg + 0.1) 1 Year, 23C 5C (2.0% of rdg + 0.1) (0.1% of rdg + 4mV) (0.4% of rdg + 8mA) (0.10% of rdg + 0.02) (0.2% of rdg + 0.2) OPEN SHORTED THERMOELECTRIC DETECTION LOAD IMPEDANCE: Stable into 1F typical. COMMON MODE VOLTAGE: 30VDC maximum. COMMON MODE ISOLATION: >109, <1500pF. MAX. VOLTAGE DROP BETWEEN INPUT/OUTPUT SENSE TERMINALS: 1 volt. MAX. SENSE LEAD RESISTANCE: 1 for rated accuracy. MAX. FORCE LEAD RESISTANCE: 0.1. SENSE INPUT IMPEDANCE: > 400k. THERMAL FEEDBACK ELEMENT SPECIFICATIONS3 Sensor Type RTD Excitation 13 Nominal Resistance Range Excitation Accuracy1,3 Nominal Sensor Temperature Range Calibration Measurement Accuracy1,3 (% rdg + offset) Thermistor Nominal Thermistor Resistance 100 1 k 10 k 100 k 100 2.5 mA 8 V max 0-1 k 2.9% -50 to +250C 1 k 833 A 8 V max 0-10 k 2.9% -50 to +250C 10 k 100 A 8 V max 0-80 k 2.9% -50 to +250C 100 k 33 A 6.6 V max 0-200 k 2.9% -50 to +250C 12% -40 to +100C 2.9% -40 to +100C , , settable , , settable 0.04 + 0.07 2 0.04 + 0.04 2 A, B, C settable 0.04 + 0.07 2 A, B, C settable 0.04 + 0.4 2 A, B, C settable 0.02 + 3 A, B, C settable 0.04 + 21 Slope & offset 0.03 + 100 nA Slope & offset 0.03 + 500 V GENERAL Accuracy vs. Temperature 0C 0.021C 0.015C 0.006C 0.009C Solid State Current Voltage Output (1ss) Output (Vss) +13.5 V 2.5 mA 833 A 15.75V max 100 1 k 2.5 mA 833 A 4 V max 0-250 0-2..50 k 1.5% 2.9% -50 to +250C -50 to +250C THERMISTOR MEASUREMENT ACCURACY19 OPTOELECTRONIC TEST SOLUTIONS TEC OUTPUT SPECIFICATIONS 25C 0.035C 0.023C 0.012C 0.014C 50C 0.070C 0.045C 0.026C 0.026C 100C 0.27C 0.18C 0.15C 0.13C OPEN/SHORTED ELEMENT DETECTION SOFTWARE LINEARIZATION FOR THERMISTOR AND RTD COMMON MODE VOLTAGE: 30VDC. COMMON MODE ISOLATION: >109, <1000pF MAX. VOLTAGE DROP BETWEEN INPUT/OUTPUT SENSE TERMINALS: 1 volt. MAX. SENSE LEAD RESISTANCE: 100 for rated accuracy. SENSE INPUT IMPEDANCE: > 1*108. Specifications 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. Keithley Instruments, Inc. (c) Copyright 2002 Keithley Instruments, Inc. Printed in the U.S.A. NOISE REJECTION: SPEED NPLC Normal 1.00 NMRR16 60 dB NOTES CMRR17 120 dB1 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, 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 (312 in x 838 in x 14916 in). Bench configuration (with handle & feet): 104mm high x 238mm wide x 370mm deep (418 in x 938 in x 14916 in). Net Weight: 3.21kg (7.08 lbs). ENVIRONMENT: Operating: 0-50C, 70% R.H. up to 35C. Derate 3% R.H./C, 35-50C. Storage: -25 to 65C 1 Model 2510 and device under test in a regulated ambient temperature of 25C. 2 With remote voltage sense. 3 1 year, 23C 5C. 4 With ILoad = 5A and VLoad = 0V. 5 With ILoad = 5A and VLoad = 10V. 6 With 10k thermistor as sensor. 7 Short term stability is defined as 24 hours with Peltier and Model 2510 at 25C 0.5C. 8 Long term stability is defined as 30 days with Peltier and Model 2510 at 25C 0.5C. 9 10Hz to 10MHz measured at 5A output into a 2 load. 10 Common mode voltage = 0V (meter connect enabled, connects Peltier low output to thermistor measure circuit ground). 11 Resistance range 0 to 20 for rated accuracy. 12 Current through Peltier > 0.2A. 13 Default values shown, selectable values of 3A, 10A, 33A, 100A, 833A, 2.5mA. Note that temperature control performance will degrade at lower currents. 14 AC Ohms is a dual pulsed measurement using current reversals available over bus only. 15 Settable to <400V and <200A in constant V and constant I mode respectively. 16 For line frequency 0.1%. 17 For 1k unbalance in LO lead. 18 Resistance range 0 to 100 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. 28775 Aurora Road * Cleveland, Ohio 44139 * 440-248-0400 * Fax: 440-248-6168 1-888-KEITHLEY (534-8453) * www.keithley.com No. 2215 5023KGW