6485-US - KEITHLEY - Datasheet.Live

LOW LEVEL MEASURE & SOURCE

www.keithley.com

1.888.KEITHLEY (U.S. only)

A Greater Measure of Conﬁdence

•Cost-effective low current

measurement solution

•10fA resolution

•5½-digit resolution

•<200µV burden voltage

•Up to 1000 readings/second

•Built-in Model 485 emulation

mode

•IEEE-488 and RS-232 interfaces

•Analog output

The 5½-digit Model 6485 Picoammeter combines

Keithley’s expertise in sensitive current measure-

ment 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 pico-

ammeters, 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.

Model 485 Model 6485

Current Ranges 2nA–2mA 2nA–20mA

Voltage Burden 200µV 200µV (1mV on

20mA range)

Reading Rate 3/s 1000/s

Digits 4½ 5½

Analog Output Yes Yes

Battery Option Yes No

Storage Buffer 100 points 2500 points

When do you need a picoammeter?

Measuring low DC currents often demands a lot more than a digital

multimeter (DMM) can deliver. Generally, DMMs lack the sensitivity required

to measure currents less than 100nA. Even at higher currents, a DMM’s

input voltage drop (voltage burden) of hundreds of millivolts can make

accurate current measurements impossible. Electrometers can measure

low currents very accurately, but the circuitry needed to measure extremely

low currents, combined with functions like voltage, resistance, and charge

measurement, can increase an electrometer’s cost signifi cantly. The Model

6485 Picoammeter combines the economy and ease of use of a DMM with

low current sensitivity near that of an electrometer.

6485

Picoammeter

Measures low currents quickly, accurately, and economically

LOW LEVEL MEASURE & SOURCE

A Greater Measure of Conﬁdence

www.keithley.com

1.888.KEITHLEY (U.S. only)

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

Ordering Information

6485 Picoammeter

Accessories Supplied

CAP-18 Protective Shield/

Cap (2-lug)

4801 Low Noise BNC Input

Cable, 1.2m (4 ft)

ACCESSORIES AVAILABLE

CABLES

4802-10 Low Noise BNC Input Cable, 3m (10 ft)

4803 Low Noise Cable Kit

7007-1 Shielded IEEE-488 Cable, 1m (3.3 ft)

7007-2 Shielded IEEE-488 Cable, 2m (6.6 ft)

7007-4 Shielded IEEE-488 Cable, 4m (13.1 ft)

7009-5 RS-232 Cable

7754-3 BNC to Alligator Cable, 0.9m (3 ft)

8607 Banana Cable set for Analog Output

8501-1 Trigger Link Cable with Male Micro-DIN Connectors at

each End, 1m (3.3 ft)

8501-2 Trigger Link Cable with Male Micro-DIN Connectors at

each End, 2m (6.6 ft)

8503 DIN-to-BNC Trigger Cable

ADAPTERS

CS-565 BNC Barrel

7078-TRX-BNC Female BNC to 3-Slot Male Triax for connecting

BNC cable into triax fixture

RACK MOUNT KITS

4288-1 Single Fixed Rack Mounting Kit

4288-2 Dual Fixed Rack Mounting Kit

GPIB INTERFACES

KPCI-488LPA IEEE-488 Interface/Controller for the PCI Bus

KUSB-488B IEEE-488 USB-to-GPIB Interface Adapter

SERVICES AVAILABLE

6485-3Y-EW 1-year factory warranty extended to 3 years from

date of shipment

C/6485-3Y-ISO 3 (ISO-17025 accredited) calibrations within 3

years of purchase*

*Not available in all countries

6485

Picoammeter

Measures low currents quickly, accurately, and economically

LOW LEVEL MEASURE & SOURCE

www.keithley.com

1.888.KEITHLEY (U.S. only)

A Greater Measure of Conﬁdence

GENERAL

INPUT CONNECTOR: BNC on rear panel.

DISPLAY: 12 character vacuum fluorescent.

RANGING: Automatic or manual.

OVERRANGE INDICATION: Display reads “OVRFLOW.”

CONVERSION TIME: Selectable 0.01 PLC to 60 PLC (50 PLC under 50Hz operation).

(Adjustable from 200µs to 1s)

READING RATE:

To internal buffer: 1000 readings/second1

To IEEE-488 bus: 900 readings/second1, 2

Notes:

1. 0.01 PLC, digital filters off, front panel off, auto zero off.

2. Binary transfer mode. IEEE-488.1.

BUFFER: Stores up to 2500 readings.

PROGRAMS: Provide front panel access to IEEE address, choice of engineering units or

scientific notation, and digital calibration.

EMC: Conforms with European Union Directive 89/336/EEC, EN61326-1.

SAFETY: Conforms with European Union Directive 73/23/EEC, EN61010-1.

TRIGGER LINE: Available, see manual for usage.

DIGITAL FILTER: Median and averaging (selectable from 2 to 100 readings).

ENVIRONMENT:

Operating: 0°–50°C; relative humidity 70% non-condensing, up to 35°C. Above 35°C,

derate humidity by 3% for each °C.

Storage: –25° to +65°C.

WARM-UP: 1 hour to rated accuracy (see manual for recommended procedure).

POWER: 100–120V or 220–240V, 50–60Hz, 30VA.

PHYSICAL:

Case Dimensions: 90mm high × 214mm wide × 369mm deep (3

in. × 83⁄8 in. × 149⁄16 in.).

Working Dimensions: From front of case to rear including power cord and IEEE-488 con-

nector: 394mm (15.5 in).

Net Weight: <2.8 kg (<6.1 lbs).

Shipping Weight: <5 kg (<11 lbs).

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: Range, Zero Check, Zero Correct, EOI (DDC mode only),

Trigger, Terminator (DDC mode only), Calibration (SCPI mode only), Display Format, SRQ,

REL, Output Format, V-offset Cal.

ADDRESS MODES: TALK ONLY and ADDRESSABLE.

LANGUAGE EMULATION: Keithley Model 485 emulation via DDC mode.

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.

Digit Accuracy (1 Year) 1Analog

Default ±(% rdg. + offset) Typical Rise Time 3

Range Resolution 18°–28°C, 0–70% RH RMS Noise 2 (10% to 90%)

2 nA 10 fA 0.4 % + 400 fA 20 fA 8 ms

20 nA 100 fA 0.4 % + 1 pA 100 fA 8 ms

200 nA 1 pA 0.2 % + 10 pA 1 pA 500 µs

2 µA 10 pA 0.15% + 100 pA 10 pA 500 µs

20 µA 100 pA 0.1 % + 1 nA 100 pA 500 µs

200 µA 1 nA 0.1 % + 10 nA 1 nA 500 µs

2 mA 10 nA 0.1 % + 100 nA 10 nA 500 µs

20 mA 100 nA 0.1 % + 1 µA 100 nA 500 µs

TEMPERATURE COEFFICIENT: 0°–18°C & 28°–50°C. For each °C, add 0.1 × (% rdg + offset) to

accuracy spec.

INPUT VOLTAGE BURDEN: <200µV on all ranges except <1mV on 20mA range.

MAXIMUM INPUT CAPACITANCE: Stable to 10nF on all nA ranges and 2µA range; 1µF on 20µA

and 200µA ranges, and on mA ranges.

MAXIMUM COMMON MODE VOLTAGE: 42V.

MAXIMUM CONTINUOUS INPUT VOLTAGE: 220 VDC.

ISOLATION (Meter COMMON to chassis): Typically >5×1011W in parallel with <1nF.

NMRR1 (50 or 60Hz): 60dB.

ANALOG OUTPUT: Scaled voltage output (inverting 2V full scale on all ranges) 3% ±2mV, 1kW

impedance.

NOTES

1. At 1 PLC – limited to 60 rdgs/second under this condition.

2. At 6 PLC, 1 standard deviation, 100 readings, filter off, capped input – limited to 10 rdgs/sec under this condition.

3. Measured at analog output with resistive load >100kW.

6485 Picoammeter

Model 6485 specifications