Lake Shore Model 330 Autotuning Temperature Controller User’s Manual
1-6
Introduction
1.3 PRECISION CALIBRATION OPTIONS
The Lake Shore Precision Calibration Option converts calibrated sensor data into breakpoint pairs readable by
the controller program. The Precision Calibration Option is available in three forms: the Model 8000 loads the
breakpoint pairs on a floppy disk in ASCII format for Customer downloading; the Model 8001 is a factory-
installed NOVRAM; the Model 8002-05 is a field-installed NOVRAM.
Precision Calibration improves specified
accuracy to 0.1K or better over a given calibration range for DT-400 Series Silicon Diode Sensors. Accuracy
for other sensors depends on the type and calibration range.
Lake Shore supplies a copy of break point information containing sensor type, sensor serial number,
maximum allowable error, break point number, voltage (or resistance), temperature, and temperature error,
along with a second sheet containing only the break point temperatures and voltages.
The Precision Calibration Option Table is a piecewise linear interpolation based on the sensor calibration.
Optimum break points are determined by an iterative procedure using weighted linear least squares defined by
either a maximum number of break points allowed or a maximum allowable error. Break point voltages are
derived from the least squares linear equations and differ from the calibration data. Differences between input
table voltages and break point voltage are converted to a corresponding error in temperature by dividing the
voltage difference by the sensitivity. Temperature errors by this method will be considerably less than by linear
interpolation between calibration data points.
1.4 ELECTROSTATIC
DISCHARGE
Electrostatic Discharge (ESD) may damage electronic parts, assemblies, and equipment. ESD is a transfer of
electrostatic charge between bodies at different electrostatic potentials caused by direct contact or induced by
an electrostatic field. The low-energy source that most commonly destroys Electrostatic Discharge Sensitive
(ESDS) devices is the human body, which generates and retains static electricity. Simply walking across a
carpet in low humidity may generate up to 35,000 volts of static electricity.
Current technology trends toward greater complexity, increased packaging density, and thinner dielectrics
between active elements, which results in electronic devices with even more ESD sensitivity. Some electronic
parts are more ESDS than others. ESD levels of only a few hundred volts may damage electronic components
such as semiconductors, thick and thin film resistors, and piezoelectric crystals during testing, handling, repair,
or assembly. Discharge voltages below 4000 volts cannot be seen, felt, or heard.
1.4.1
Identification of Electrostatic Discharge Sensitive Components
Below are various industry symbols used to label components as ESDS:
1.4.2
Handling Electrostatic Discharge Sensitive Components
Observe all precautions necessary to prevent damage to ESDS components before attempting installation.
Bring the device and everything that contacts it to ground potential by providing a conductive surface and
discharge paths. As a minimum, observe these precautions:
1. Deenergize or disconnect all power and signal sources and loads used with unit.
2. Place unit on a grounded conductive work surface.
3. Ground technician through a conductive wrist strap (or other device) using 1 M
Ω
series resistor to protect
operator.
4. Ground any tools, such as soldering equipment, that will contact unit. Contact with operator's hands
provides a sufficient ground for tools that are otherwise electrically isolated.
5. Place ESDS devices and assemblies removed from a unit on a conductive work surface or in a conductive
container. An operator inserting or removing a device or assembly from a container must maintain contact
with a conductive portion of the container. Use only plastic bags approved for storage of ESD material.
6. Do not handle ESDS devices unnecessarily or remove from the packages until actually used or tested.