To Next Page

To Previous Page

Model 2657A High Power System SourceMeter® Instrument Reference Manual Section 4: Theory of operation

2657A-901-01 Rev. B/December 2012 4-19

Source I

When the instrument is configured to source current (I-source), as shown in the figure below, the

instrument functions as a high-impedance current source with voltage limit capability and can

measure current (I-meter) or voltage (V-meter).

For 2-wire local sensing, voltage is measured at the input/output terminals of the instrument. For 4-

wire remote sensing, voltage is measured directly at the device under test (DUT) using the sense

terminals. This eliminates any voltage drops that may be in the test leads or connections between the

instrument and the DUT.

The current source does not require or use the sense leads to enhance current source accuracy.

However, if the instrument is in 4-wire remote sense mode, the instrument may reach limit levels if the

sense leads are disconnected. With 4-wire remote sensing selected, the sense leads must be

connected or incorrect operation will result.

Figure 85: Source I configuration

Remote

SENSE HI

Remote

I-source

V-meter

SENSE LO

Local

GUARD

–

I-meter

Feedback

NOTES: 1. This represents a protection circuit. Do not apply more than 3030 V

between HI and SENSE HI. To maintain optimal operation and obtain

accurate measurements, the maximum voltage between HI and

SENSE HI should be no more than 3 V. This limit also applies to the

maximum voltage between LO and SENSE LO.

2. Approximately 80 kΩ.

Keithley 2657A User Manual

Questions and Answers: