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8 - Manual setup
Limits and Protection
64
SMU4000 Series Instruction Manual
Limits and Protection
CNFG >
[Source Measure Action] Manual Setup
>
[Source] Control and Limits
Various methods of protection are provided to protect the test setup from damage by
unexpected occurrences.
Limits
The limit setting (also known as compliance) provides a limit to ensure that the instrument
cannot source or sink a voltage or current beyond that set limit.
The main purpose is to prevent damage to the device under test when set to a suitable level.
For both voltage and current limits there is only one setting to cover both polarities which
provides dual polarity limiting. For example, setting a limit of 1A, sets the dual polarity current
limits to +/- 1A.
When a limit is breached the source voltage/ current is restricted to the limit setting, the
corresponding CV / CC LED is illuminated, VLIMIT/ ALIMIT is shown in the results box of the
home screen and the colour of the appropriate measurement on the home screen is changed to
orange. Both computed readings (power and resistance) also turn orange.
The limit is not latched and can recover if the source level is reduced or the load changes
accordingly.
When manually selecting ranges, the limit level can be set between 10% and 105% of the
selected range.
The combination of the source and limit level settings cannot exceed the instruments maximum
power of 25W.
Limits can be added depending on the mode of operation:
Mode
Limits
SV (Source Voltage)
Current limits for both polarities
SC (Source Current)
Voltage limits for both polarities
LC (Load Current)
Voltage dropout
LR (Load Resistance)
Current limit and Voltage dropout
LP (Load Power)
Current limit and Voltage dropout
MV (Measure Voltage)
-
MC (Measure Current)
-
MR (Measure Resistance)
Voltage limit for both polarities
MHR (Measure Resistance)
Current limit for both polarities
NOTE
Setting a limit too close to the desired output level can result in extended source rise times. The
source is slewed slightly when approaching (and predicting to exceed a limit) in order to enter
the limit smoothly. Changing the limit in real time can also temporarily extend consequent
source level change rise times. Ideally delay any source changes by 250ms after changing the
limit, to maintain expected rise times.