Keithley Instruments 6487 Data Sheet

6487 Picoammeter/ Voltage Source

The 51⁄2-digit Model 6487 Picoammeter/Voltage
Source improves on the measurement capability
of the award-winning Model 6485, and adds a
high resolution 500V source. It provides higher
accuracy and faster rise times than the 6485, as
well as a damping function for use with capaci­tive devices. With eight current measurement
ranges and high speed autoranging, this cost­effective instrument can measure currents from
20fA to 20mA, take measurements at speeds up
to 1000 readings per second, and source voltage
from 200µV to 505V.

The Model 6487’s 10fA resolution, superior sen
sitivity, voltage sweeping, and Alternating Voltage
resistance measurements make it well suited for
characterizing low current devices. Using the lat
est current measurement technology, it is signifi­cantly less expensive than other instruments that
perform similar functions, such as optical power
meters, tera-ohmmeters, competitive picoamme-

ters, or user-designed solutions. With a price
that’s comparable to a high-end DMM, the Model 6487 makes picoamp-level measurements afford­able for virtually any laboratory or production floor.

-

-

• 10fA resolution

1

⁄2-digit resolution

• 5

• <200µV burden voltage

• Alternating Voltage method

ohms measurements

• Automated voltage sweeps for

I-V characterization

• Floating measurements up to

500V

Measures low currents and high resistances quickly, accurately, and economically

Up to 1000 readings/second

•

Built-in Model 486 and 487

•

emulation mode

• IEEE-488 and RS-232 interfaces

• Analog output

• Digital I/O

• Driver for LabVIEW™,

LabWindows

™

/CVI, Visual Basic®,

C/C++, and TestPoint

• ExceLINX

™

Excel®Add-In

included

™

included

Low Voltage Burden and Higher Accuracy

While DMMs typically employ shunt ammeter circuitry to measure current, the Model 6487 is a feed­back 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 6487 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 487

The Model 6487 builds on the strengths of one
of Keithley’s most popular picoammeters, the
Model 487, offering an additional 20mA meas­urement range, as well as much higher measure­ment speeds, up to 1000 readings per second. It
simplifies device characterization with built-in
voltage sweeping capability and the Alternating
Voltage method for high resistances. A time­stamped 3000-reading data buffer provides mini­mum, maximum, and standard deviation statis

-

tics. A built-in emulation mode makes it possible

Current Ranges 2 nA–2 mA 2 nA–20 mA
Voltage Burden 200 µV 200 µV

Reading Rate Up to 180/s Up to 1000/s
Voltage Sweeps No Yes
Alternating

Voltage Ohms
Analog Output Yes Yes

Storage Buffer 512 points 3000 points
Best V Source

Resolution

Model 487 Model 6487

(1 mV on

20 mA range)

No Y

(non-inverting) (inverting)

1 mV 0.2 mV

es

to control the Model 6487 with any custom code
written to control the Model 487.

Features that Expand Test and Measurement Flexibility

• Direct resistance measurements. Optimized for resistances from 50Ω to 5×1014Ω using the

Source Voltage/Measure Current method.

• Alternating Voltage method resistance measurements. This method improves resistance meas­urements on devices with high background current or high noise. It extends the measurable resist­ance range up to 10

•

500V overload protection. This high overload protection and a robust design let the Model 6487

16

Ω.

tolerate abusive overflows, including accidentally shorting the voltage source directly into the
ammeter.

1.888.KEITHLEY (U.S. only)

LOW LEVEL MEASUR E & SOURCE

www.keithley.com

A GREATER MEASURE OF CONFIDENCE

Photo Diode

Ammeter

V

source

Calibrated Light Source

Probe

Needles

Wafer

Pads

Probe Needles

6487 Picoammeter/Voltage Source

6487 Picoammeter/ Voltage Source

• Rear panel triax input. This allows the picoammeter to be used in floating operation, up to 500V.

Ordering Information

487 Picoammeter/Voltage

6

Accessories Supplied

CA-186-1B

CAP-31 Protective Shield/Cap

S-459 Safety Interlock Plug

C
7078-TRX-3

8607 High Voltage Banana

Extended warranty, service, and
calibration contracts are available.

Source

Ground Connection
Cable, Banana to Screw­Lug

(3-lug)

Low Noise Triax Input
Cable, 1m (3 ft)

Cable Set for Voltage
Source Output

When not floating, the addition of a triax to BNC adapter allows inexpensive, easy-to-use BNC
cables to be employed, rather than more expensive triaxial cables.

• RS-232 and IEEE-488 interfaces. These interfaces make it easy to integrate the Model 6487 into
automated test and measurement systems.

•

Scaled voltage analog output. This output allows the Model 6487 to transmit measurement
results to devices like DMMs, data acquisition cards, oscilloscopes, or strip chart recorders.

Built-in Trigger Link interface. The Trigger Link interface simplifies synchronizing the Model

•
6487 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.

• Display on/off switch. For research on light-sensitive components, such as measuring the dark
currents of photodiodes or I-V measurements on unpackaged semiconductors, the front panel dis­play can be switched off to avoid introducing light that could significantly reduce the accuracy of
the results.

One-touch front panel design. Functions can be configured easily with the push of a button,

•
without complicated function menus.

A Broad Range of Low Current Applications

Wafer-Level Photodiode Testing

The Model 6487 Picoammeter/Voltage Source can be paired with a calibrated light source and a prob­ing fixture to create a cost-effective photodiode test system. Multiple Model 6487s can be connected
to the DUT’s probe pads to provide photocurrent readings or, with the addition of a switch matrix,
one picoammeter can take current measurements from multiple pads. In the first step of the meas­urement process, performed in total darkness, the Model 6487 produces a voltage sweep and then
measures the resulting dark current. In the second step, a voltage bias is applied and the resulting
photocurrent is measured while the light level is increased in calibrated steps. The same basic test
configuration can be used for testing positive intrinsic negative (PIN) and avalanche photodiodes
(APDs). The 6487’s high resolution on the 10V source range provides superior sweeping and biasing
when small biases are required. The 500V source capability is necessary to bias APDs.

APPLICATIONS

Resistance/resistivity

•
measurements

• Beam monitoring and radiation
monitoring

• Leakage current testing in
insulators, switches, relays, and
other components

• I-V characterization on
semiconductor and
optoelectronic devices

• Fiber alignment

• Circuit test and analysis in DCLF
circuits

• Sensor characterization

1.888.KEITHLEY (U.S. only)

www.keithley.com

A GR

EA

TER M

EASU

RE OF CONFIDENCE

Measures low currents and high resistances quickly, accurately, and economically

LOW LEVEL MEASUR E & SOURCE