Keithley 580

Manuals – Specifications – Links – Pictures

The Keithley 580 is a 4½-digit autoranging microohmmeter.

Key Specifications

Resistance	200 mΩ to 200 kΩ in decade ranges (4-wire)
Resolution	10 μΩ to 10 Ω
Display	4½ digits (±20,000 counts), 7-segment LCD
Test Current	100 mA to 10 µA
Power	105–125 or 210-250 V, 50–60 Hz, 12 VA
Features	DC or pulsed drive current Positive or negative drive current Dry-contact mode (max. 20 mV open voltage) External Trigger input

Standard accessories: 5801 Lead Pouch, 5804 Test Lead Set, 5805 Kelvin Probes, 5806 Kelvin Clips, Operator's and Service Manuals.

Options

• Rechargeable Battery Pack (Model 1978), 6 hours runtime
• Isolated analog output / IEEE-488 Interface (Model 5802)

Links

• Low Resistance Micro-Ohmmeter: Keithley 580 Review @ YouTube

Internals

The Keithley 580 performs four-wire measurements using a ratiometric measurement principle. A series circuit is formed between a voltage source, a reference resistor (10 Ω / 100 Ω / 1 kΩ / 100 kΩ), and the unknown resistor, with the same current flowing through both the reference and unknown resistors.

The source current is supplied through a MOSFET full bridge. It can be set for DC drive in either polarity, or pulsed at about 3 Hz. To cancel thermal EMFs, the 580 takes an offset measurement before the source current is turned on. In DC Drive mode this happens once when switching from STBY (standby) to OPR (operate), therefore the test leads need to be connected beforehand.

The sense voltage passes through a ×100 instrumentation amplifier to a single-slope A/D converter.

In Dry Circuit Test mode (200 mΩ to 20 Ω ranges), the open circuit voltage is kept below 20 mV by shunting one of three precision resistors (0.15 Ω / 1.9 Ω / 14 Ω) across the source terminals.

Pictures

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  5805 leads

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  5805 tips

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  Internal

Better pictures needed - please contribute

Components

Some Parts Used in the Keithley 580