Section 3: Functions and features Model 2657A High Power System SourceMeter® Instrument Reference Manual
3-66 2657A-901-01 Rev. B/December 2012
Command interface
Turning on High-C mode has the following effects on the SMU settings:
• smua.measure.autorangei is set to smua.AUTORANGE_FOLLOW_LIMIT and cannot be
changed.
• Current ranges below 1 μA are not accessible.
• If smua.source.limiti is less than 1 μA, it is raised to 1 μA.
• If smua.source.rangei is less than 1 μA, it is raised to 1 μA.
• If smua.source.lowrangei is less than 1 μA, it is raised to 1 μA.
• If smua.measure.lowrangei is less than 1 μA, it is raised to 1 μA.
Measuring current
The following inputs are required to test leakage using the factory leakage script, as shown in the
script example below.
• SMU: Sets the Model 2657A source-measure unit to use
• levelv: Sets the output voltage level
• limiti: Sets the current limit for discharging or charging the capacitor
• sourcedelay: Solve the following equation to determine the amount of time before taking a current
reading:
Where: i is the limiti setting (current limit)
• measurei: Sets the current measure range
• measuredelay: Defines the delay to wait after lowering the current limit before taking the measurement
Script example
Use the smua.source.highc attribute to set and control the options for high-capacitance mode,
charge a capacitor, and test for leakage.
The following programming example (and figure) illustrates how to enable high-capacitance mode on
SMU A.
1. To enable high-capacitance mode, send:
-- Enables high-capacitance mode.
smua.source.highc = smua.ENABLE
iC
Δv
Δt
------
=
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