Model 2657A High Power System SourceMeter® Instrument Reference Manual
Section 3: Functions and features
2657A-901-01 Rev. B/December 2012
3-85
Operation
When sourcing, the output of the Model 2657A can only be turned on when the interlock line is driven
high through a switch to +5 V (as shown). If the lid of the test fixture opens, the switch opens, and the
interlock line goes low, turning the output of the High Power System SourceMeter
®
instrument off.
The output is not automatically turned on when the interlock line is set high. The output cannot be
turned back on until the interlock line is set high.
A signal of > 4 V at 50 mA (at an absolute maximum of 6 V) must be externally applied to this pin to
ensure operation. This signal is pulled down to chassis ground with a 10 k
Ω
resistor. Operation will be
blocked when the interlock signal is < 4 V.
Figure 67: Safety interlock pin
To help troubleshoot interlock errors, the Model 2657A provides an error code that is associated with
this feature. This is error code 1122, "Interlock power power supply failure." This error indicates that
either:
•
The interlock appears to be engaged, but the high-voltage power supply is not active. Causes of
this include:
-
The power supply is nonfunctional.
-
The interlock pin is at an intermediate voltage above 2 V but below 5 V. This value could be high
enough to be recognized as a logical true (1) by the digital hardware, but not high enough to engage the
interlock relay.
•
The interlock is engaged, but the main SMU fan is not rotating.
to 120 V AC or
240 V AC input
5 V DC out
(pin 22)
Interlock in
(pin 24)
Interlock signal
to firmware
Coil resistance
100 ohms ±10%
Power supply for
display and interfaces
High voltage
power supply
Test fixture
with
interlock
switch
Power switch
Summary of Contents for 2657A
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