The 5½-digit Model 6485 Picoammeter combines Keithley’s expertise in sensitive current measurement instrumentation with enhanced speed and a robust design. With eight current measurement ranges and high speed autoranging, this cost-effective instrument can measure currents from 20fA to 20mA, taking measurements at speeds up to 1000 readings per second.

The Model 6485’s 10fA resolution and superior sensitivity make it well suited for characterizing low current phenomena, while its 20mA range lets it measure currents high enough for applications such as measuring 4-20mA sensor loops.

Although it employs the latest current measurement technology, it is significantly less expensive than other instruments that perform similar functions, such as optical power meters, competitive picoammeters, or user-designed solutions. With a price that’s comparable to a general purpose DMM, the Model 6485 makes picoamp-level measurements affordable for virtually any laboratory or production floor.

Low Voltage Burden and Higher Accuracy

While DMMs typically employ shunt ammeter circuitry to measure current, the Model 6485 is a feed-back picoammeter. This design reduces voltage burden by several orders of magnitude, resulting in a voltage burden of less than 200µV on the lower measurement ranges. The low voltage burden makes the Model 6485 function much more like an ideal ammeter than a DMM, so it can make current measurements with high accuracy, even in circuits with very low source voltages.

Successor to the Model 485

The Model 6485 builds on the strengths of one of Keithley’s most popular picoammeters, the Model 485, offering an additional 20mA measurement range, as well as much higher measurement speeds. With a top speed of up to 1000 readings per second, the Model 6485 is the fastest picoammeter Keithley has ever made. It offers ten times greater resolution than the Model 485 on every range. A time-stamped 2500-reading data buffer provides minimum, maximum, and standard deviation statistics. A built-in emulation mode simplifies upgrading existing applications originally configured with a Model 485. This emulation mode makes it possible to control the Model 6485 with any custom code written to control the Model 485. Refer to the comparison table for additional information.

Features that Expand Test and Measurement Flexibility

• Scaled voltage analog output. This output allows the Model 6485 to transmit measurement results to devices like DMMs, data acquisition boards, oscilloscopes, or strip chart recorders.
• 220V overload protection. This high overload protection and a robust design let the Model 6485 withstand abusive overflows.
• One-touch front panel design. Functions can be configured easily with the push of a button, without complicated function menus.
• Built-in Trigger Link interface. The Trigger Link interface simplifies synchronizing the Model 6485 with other instruments and voltage sources. This interface combines six independent selectable trigger lines on a single connector for simple, direct control over all instruments in a system.
• RS-232 and IEEE-488 interfaces. These interfaces make it easy to integrate the Model 6485 into automated test and measurement systems.
• Display on/off switch. For research on light-sensitive components, such as measuring the dark currents of photodiodes, the front panel display can be switched off to avoid introducing light that could significantly reduce the accuracy of the results.
• REL and LOG functions. The Model 6485 can make relative readings with respect to a baseline value or display the logarithm of the absolute value of the measured current.
• Resistance calculations. The Model 6485 can calculate resistance by dividing an externally sourced voltage value by the measured current.
• Rear panel BNC inputs. Inexpensive, easy-to-use BNC cables can be employed, rather than more expensive triax cables.

APPLICATIONS

• Beam monitoring and radiation monitoring
• Leakage current testing in insulators, switches, relays, and other components
• SEM beam current measurements
• Galvanic coupling measurements
• Optoelectronic device testing and characterization
• Optical fiber alignment
• Circuit test and analysis in DCLF circuits
• Sensor characterization
• I-V measurements of semiconductors and other devices
• Nanoelectronic device characterization
• Capacitor leakage
• Teaching labs