Programmable Electrometer The Model 6514 Electrometer combines flexible interfacing capabilities with current sensitivity, charge measurement capabilities, resolution, and speed that are equal or superior to our earlier electrometers. The Model 6514's built-in IEEE-488, RS-232, and digital I/O interfaces make it simple to configure fully automated, high speed systems for low-level testing. The 51/2-digit Model 6514 is designed for applications that demand fast, yet precise measurements of low currents, voltages from high resistance sources, charges, or high resistances. The Model 6514's exceptional measurement performance comes at an affordable price. While its cost is comparable with that of many high end DMMs, the Model 6514 offers far greater current sensitivity and significantly lower voltage burden (as low as 20V) than other instruments can provide. * High speed--up to 1200 readings/second R&D on a Budget The Model 6514 offers the flexibility and sensitivity needed for a wide array of experiments, providing better data far faster than older electrometer designs. Applications include measuring currents from light detectors and other sensors, beam experiments, and measuring resistances using a current source. In addition to use by researchers in areas such as physics, optics, and materials science, the Model 6514's affordable price makes it an attractive alternative to high end DMMs for low current measurement applications, such as testing resistance and leakage current in switches, relays, and other components. For more information on how the Model 6514 does this, refer to the section titled "Low Voltage Burden." * Interfaces readily with switches, computers, and component handlers The Model 6514 builds on the features and capabilities of the Keithley electrometers that preceded it. For example, like those instruments, a built-in constant current source simplifies measuring resistance. * Cancels voltage and current offsets easily Two analog outputs--a 2V output and a preamp output--are available for recording data with stripchart recorders. * <1fA noise * >200TW input impedance on voltage measurements * Charge measurements from 10fC to 20C ACCESSORIES AVAILABLE Ordering Information LOW LEVEL MEASURE & SOURCE 6514 Programmable Electrometer Accessories Supplied 237-ALG-2 Low Noise Triax Cable, 3-Slot Triax to Alligator Clips, 2m (6.6 ft) Services Available 6514-3Y-EW 1-year factory warranty extended to 3 years from date of shipment C/6514-3Y-ISO 3 (ISO-17025 accredited) calibrations within 3 years of purchase* TRN-LLM-1-C Course: Making Accurate Low-Level Measurements *Not available in all countries CABLES 237-ALG-2 7007-1 7007-2 7009-5 7078-TRX-3 7078-TRX-10 7078-TRX-20 8501-1 8501-2 Low Noise Triax Cable, 3-Slot Triax to Alligator Clips Shielded IEEE-488 Cable, 1m (3.3 ft) Shielded IEEE-488 Cable, 2m (6.6 ft) RS-232 Cable Low Noise Triax Cable, 3-Slot Triax Connectors, 0.9m (3 ft) Low Noise Triax Cable, 3-Slot Triax Connectors, 3m (10 ft) Low Noise Triax Cable, 3-Slot Triax Connectors, 6m (20 ft) Trigger-Link Cable, 1m (3.3 ft) Trigger-Link Cable, 2m (6.6 ft) ADAPTERS 7078-TRX-BNC 3-Lug Triax to BNC Adapter 237-TRX-NG Triax Male-Female Adapter with Guard Disconnected 237-TRX-T 3-Slot Male Triax to Dual 3-Lug Female Triax Tee Adapter 237-TRX-TBC 3-Lug Female Triax Bulkhead Connector (1.1kV rated) 7078-TRX-TBC 3-Lug Female Triax Bulkhead Connector with Cap GPIB Interfaces KPCI-488LPA IEEE-488 Interface/Controller for the PCI Bus KUSB-488B IEEE-488 USB-to-GPIB Interface Adapter RACK MOUNT KITS 4288-1 Single Fixed Rack Mounting Kit 4288-2 Dual Fixed Rack Mounting Kit 1.888.KEITHLEY (U.S. only) www.keithley.com A Greater Measure of Confidence Fast, precise current, charge, voltage, and resistance measurements Fast, precise current, charge, voltage, and resistance measurements 6514 Economical Component Testing Once, electrometers were simply considered too slow to keep up with the high throughput that production test applications demand. The Model 6514 is designed for fast, sensitive measurements, providing speeds up to 1200 readings per second with fast integration or 17 measurements per second with 60Hz line-cycle integration. It offers 10fA resolution on 2nA signals, settling to within 10% of the final value in just 15ms. A normal-mode rejection ratio (NMRR) of 60dB allows making accurate low current measurements, even in the p resence of line frequency induced currents, which is a common concern in production floor environments. The instrument's sensitivity makes it easy to determine the leakage resistance on capacitances up to 10nF or even on higher capacitances when a series resistor is used. While the Model 6514 can be easily operated manually using the front panel controls, it can also be externally controlled for automated test applications. Built-in IEEE-488 and RS232 interfaces make it possible Electrometer Leakage Resistance RL IL Photodiode (no incident light) ID - + A/D VBURDEN (error current due to VBURDEN) Figure 1. Dark Current Measurement with Burden Voltage Uncorrected 6514 Electrometer RL IL = 0 Photodiode (no incident light) ID - + VBURDEN CAL VOFFSET A/D Total offset voltage = 0 Figure 2. Dark Current Measurement with Burden Voltage Corrected to program all instrument functions over the bus through a computer controller. The instrument's interfaces also simplify integrating external hardware, such as sources, switching systems, or other instruments, into the test system. A digital I/O interface can be used to link the Model 6514 to many popular component handlers for tight systems integration in binning, sorting, and similar applications. These features make the Model 6514 a powerful, low cost tool for systems designed to test optical devices and leakage resistance on low-value capacitors, switches, and other devices, particularly when the test system already includes a voltage source or when the source current/measure voltage technique is used to determine r esistance. Low Voltage Burden The Model 6514's feedback ammeter design minimizes voltage offsets in the input circuitry, which can affect current measurement accuracy. The instrument also allows active cancellation of its input voltage and current offsets, either manually via the front panel controls or over the bus with IEEE-488 commands. Dark Current Measurements When measuring dark currents (Figure 1) from a device such as a photodiode, the ammeter reads the sum of two different currents. The first current is the dark current (I D) generated by the detector with no light falling upon the device (in other words, the signal of interest); the second one is the leakage current (I L) generated by the voltage burden (V BURDEN) appearing at the terminals of the ammeter. In a feedback ammeter, the primary "voltage burden" is the amplifier offset voltage. This leakage current represents an error current. Without the use of cancellation techniques, I L = V BURDEN/R L. Figure 2 illustrates how the Model 6514's CAL VOFFSET is adjusted to cancel V BURDEN to within the voltage noise level of a few microvolts, so the measured current is only the true dark current (ID) of the photodiode. In a similar manner, offset currents can also be cancelled. Earlier electrometers used an internal numerical correction technique in which the voltage burden was still present, so the measured dark current included the error term I L = V BURDEN/R L. Voltage Burden and Measurement Error Electrometers provide current measurement with lower terminal voltage than is possible when making DMM measurements. As shown in Figure 3, DMMs measure current using a shunt resistance that develops a voltage (typically 200mV full-range) in the input circuit. This creates a terminal voltage (V BURDEN) of about 200mV, thereby lowering the measured current. Electrometers reduce this terminal v oltage by using the feedback ammeter configuration illustrated in Figure 1. The Model 6514 lowers this terminal voltage still further--to the level of the voltage noise--by canceling out the small offset voltage that remains, as shown in Figure 2. Any error signals that remain are n egligible in comparison to those that can occur when m easuring current with a DMM. 1.888.KEITHLEY (U.S. only) www.keithley.com A Greater Measure of Confidence Fast, precise current, charge, voltage, and resistance measurements Programmable Electrometer LOW LEVEL MEASURE & SOURCE Fast, precise current, charge, voltage, and resistance measurements 6514 6514 Programmable Electrometer VOLTSAccuracy DMM R + - VBURDEN = 200mV at full range VSOURCE Model 6514 specifications A/D Desired Current Reading: Notes 1.When properly zeroed, 51/2-digit. Rate: Slow (100ms integration time). I= DMM's Actual Current Reading: I = VSOURCE R VSOURCE - VBURDEN R Figure 3. Errors Due to Burden Voltage when Measuring with a DMM The example below compares a DMM's voltage burden errors with the 6514's. If: VSOURCE = 1V, R = 50kW 1V The desired current reading is: I = = 20A 50kW Actual Reading (20A range on DMM): VBURDEN = 200mV I= Refer to Figure 3. 1V - 200mV 800mV = = 16A = 20% Burden error 50kW 50kW with a DMM 6514 Actual Reading: VBURDEN = 10V Refer to Figure 2. I= Temperature Coefficient 0-18C & 28-50C (%rdg+counts)/C 0.003 + 2 0.002 + 1 0.002 + 1 0 .999990V = 19 .9998A = 0.001% Burden error 50kW with the 6514 DMMOffset Currents Typically, offset currents in DMMs are tens or hundreds of picoamps, which severely limits their low current measuring capabilities compared to the Model 6514 with 3fA input bias current. NMRR: 60dB on 2V, 20V, >55dB on 200V, at 50Hz or 60Hz 0.1%. CMRR: >120dB at DC, 50Hz or 60Hz. INPUT IMPEDANCE: >200TW in parallel with 20pF, <2pF guarded (10MW with zero check on). SMALL SIGNAL BANDWIDTH AT PREAMP OUTPUT: Typically 100kHz (-3dB). AMPS 51/2-Digit RangeResolution 20 pA 100 aA 2 200 pA 1 fA 2 2 nA 10 fA 20 nA 100 fA 200 nA 1 pA 2 A 10 pA 20 A 100 pA 200 A 1 nA 2 mA 10 nA 20 mA 100 nA Accuracy (1 Year)1 18-28C (%rdg+counts) 1 + 30 1 + 5 0.2 + 30 0.2 + 5 0.2 + 5 0.1 + 10 0.1 + 5 0.1 + 5 0.1 + 10 0.1 + 5 Temperature Coefficient 0-18C & 28-50C (%rdg+counts)/C 0.1 + 5 0.1 + 1 0.1 + 2 0.03 + 1 0.03 + 1 0.005 + 2 0.005 + 1 0.005 + 1 0.008 + 2 0.008 + 1 Notes 1.When properly zeroed, 51/2-digit. Rate: Slow (100ms integration time). 2.aA =10 -18A, fA=10 -15A. INPUT BIAS CURRENT: <3fA at Tcal (user adjustable). Temperature coefficient = 0.5fA/C. INPUT BIAS CURRENT NOISE: <750aA p-p (capped input), 0.1Hz to 10Hz bandwidth, damping on. Digital filter = 40 readings. INPUT VOLTAGE BURDEN at Tcal 1C (user adjustable): <20V on 20pA, 2nA, 20nA, 2A, 20A ranges. <100V on 200pA, 200nA, 200A ranges. <2mV on 2mA range. <4mV on 20mA range. TEMPERATURE COEFFICIENT OF INPUT VOLTAGE BURDEN: <10V/C on pA, nA, A ranges. PREAMP SETTLING TIME (to 10% of final value): 2.5s typical on pA ranges, damping off, 3s typical on pA ranges damping on, 15ms on nA ranges, 5ms on A and mA ranges. NMRR: >95dB on pA, 60dB on nA, A, and mA ranges at 50Hz or 60Hz 0.1%. Digital Filter = 40. OHMS LOW LEVEL MEASURE & SOURCE APPLICATIONS * High resistivity measurements * Leakage currents * Ion selective electrode measurements * pH measurements * Conductivity cells * Potentiometry Accurac y Temperature (1 Year)1 Coefficient 18-28C 0-18C & 28-50C 51/2-Digit (% rdg+counts) (% rdg+counts)/C RangeResolution 2 kW 10 mW 0.20 + 10 0.01 + 2 20 kW 100 mW 0.15 + 3 0.01 + 1 200 kW 1 W 0.25 + 3 0.01 + 1 2 MW 10 W 0.25 + 4 0.02 + 2 20 MW 100 W 0.25 + 3 0.02 + 1 200 MW 1 kW 0.30 + 3 0.02 + 1 2 GW 10 kW 1.5 + 4 0.04 + 2 20 GW 100 kW 1.5 + 3 0.04 + 1 200 GW 1 MW 1.5 + 3 0.04 + 1 Test Current (nominal) 0.9 mA 0.9 mA 0.9 mA 0.9 A 0.9 A 0.9 A 0.9 nA 0.9 nA 0.9 nA Notes 1. When properly zeroed, 51/2-digit. Rate: Slow (100ms integration time). maximum open circuit voltage: 250V DC. preamp settling time (To 10% of final reading with <100pF input capacitance): 2kW through 200kW: 2ms; 20MW through 200MW: 90ms. 2GW through 200GW: 1s. 1.888.KEITHLEY (U.S. only) www.keithley.com A Greater Measure of Confidence Model 6514 specifications I 51/2-Digit RangeResolution 2V 10 V 20 V 100 V 200 V 1 mV (1 Year)1 18-28C (%rdg+counts) 0.025 + 4 0.025 + 3 0.06 + 3 6514 Programmable Electrometer 61/2-Digit RangeResolution 20 nC 10 fC 200 nC 100 fC 2 C 1 pC 20 C 10 pC (1 Year)1, 2 18-28C (%rdg+counts) 0.4 + 50 0.4 + 50 1 + 50 1 + 50 Temperature Coefficient 0-18C & 28-50C (%rdg+counts)/C 0.04 + 10 0.04 + 10 0.05 + 10 0.05 + 10 Notes: 1.Charge acquisition time must be <1000s, derate 2% for each additional 10,000s. 2.When properly zeroed, 61/2-digit. Rate: Slow (100ms integration time). IEEE-488 BUS IMPLEMENTATION MULTILINE COMMANDS: DCL, LLO, SDC, GET, GTL, UNT, UNL, SPE, SPD. IMPLEMENTATION: SCPI (IEEE-488.2, SCPI-1996.0); DDC (IEEE-488.1). UNILINE COMMANDS: IFC, REN, EOI, SRQ, ATN. INTERFACE FUNCTIONS: SH1, AH1, T5, TE0, L4, LE0, SR1, RL1, PP0, DC1, DT1, C0, E1. PROGRAMMABLE PARAMETERS: Function, Range, Zero Check, Zero Correct, EOI (DDC mode only), Trigger, Terminator (DDC mode only), Data Storage 2500 Storage, Calibration (SCPI mode only), Display Format, SRQ, REL, Output Format, Guard, V-offset Cal, I-offset Cal. ADDRESS MODES: TALK ONLY and ADDRESSABLE. LANGUAGE EMULATION: 6512, 617, 617-HIQ emulation via DDC mode. TRIGGER TO READING DONE: 150ms typical, with external trigger. RS-232 IMPLEMENTATION: Supports: SCPI 1996.0. Baud Rates: 300, 600, 1200, 2400, 4800, 9600, 19.2k, 38.4k, 57.6k. Protocols: Xon/Xoff, 7 or 8 bit ASCII, parity-odd/even/none. Connector: DB-9 TXD/RXD/GND. Model 6514 rear panel LOW LEVEL MEASURE & SOURCE Model 6514 specifications INPUT BIAS CURRENT: <4fA at Tcal. Temperature coefficient = 0.5fA/C. GENERAL OVERRANGE INDICATION: Display reads "OVRFLOW." RANGING: Automatic or manual. CONVERSION TIME: Selectable 0.01PLC to 10PLC. PROGRAMS: Provide front panel access to IEEE address, choice of engineering units or scientific notation, and digital calibration. MAXIMUM INPUT: 250V peak, DC to 60Hz sine wave; 10s per minute maximum on mA ranges. MAXIMUM COMMON MODE VOLTAGE (DC to 60Hz sine wave): Electrometer, 500V peak. ISOLATION (Meter COMMON to chassis): Typically 1010W in parallel with 500pF. INPUT CONNECTOR: Three lug triaxial on rear panel. 2V ANALOG OUTPUT: 2V for full range input. Inverting in Amps and Coulombs mode. Output impedance 10kW. PREAMP OUTPUT: Provides a guard output for Volts measurements. Can be used as an inverting output or with external feedback in Amps and Coulombs modes. digital interface: Handler Interface: Start of test, end of test, 3 category bits. Digital I/O: 1 Trigger input, 4 outputs with 500mA sink capability. Connector: 9 pin D subminiature, male pins. EMC: Conforms with European Union Directive 89/336/EEC EN55011, EN50082-1, EN61000-3-2, EN61000-3-3, FCC part 15 class B. SAFETY: Conforms with European Union Directive 73/23/EEC EN61010-1. GUARD: Switchable voltage and ohm guard available. TRIGGER LINE: Available, see manual for usage. READING STORAGE: 2500 readings. READING RATE: To internal buffer 1200 readings/second1 To IEEE-488 bus 500 readings/second1, 3 To front panel 17 readings/second at 60Hz;2 15 readings/second at 50Hz.2 Notes: 1 0.01PLC, digital filters off, front panel off, auto zero off. 2 1.00PLC, digital filters off. 3 Binary transfer mode. DIGITAL FILTER: Median and averaging (selectable from 2 to 100 readings). Damping: User selectable on Amps function. ENVIRONMENT: Operating: 0-50C; relative humidity 70% non-condensing, up to 35C. Storage: -25 to +65C. WARM-UP: 1 hour to rated accuracy (see manual for recommended procedure). POWER: 90-125V or 210-250V, 50-60Hz, 60VA. PHYSICAL: Case Dimensions: 90mm high x 214mm wide x 369mm deep (31/2 in. x 83 8 in. x 149 16 in.). Working Dimensions: From front of case to rear including power cord and IEEE-488 connector: 15.5 inches. Net Weight: <4.6kg (<10.1 lbs). Shipping Weight: <9.5kg (<21 lbs). Model 6514 specifications COULOMBSAccuracy 1.888.KEITHLEY (U.S. only) www.keithley.com A Greater Measure of Confidence