Overheating Protection; Power Equations To Avoid Overheating - Tektronix KEITHLEY System SourceMeter 2636B Reference Manual

Section 7: Theory of operation
As an example, assume the following:
System SourceMeter
Device under test (DUT) resistance: 10 Ω
With a source voltage of 10 V and a DUT resistance of 10 Ω, the current through the DUT should be:
10 V / 10 Ω = 1 A. However, because the limit is set to 10 mA, the current will not exceed that value,
and the voltage across the resistance is limited to 100 mV. In effect, the 10 V voltage source is
transformed into a 10 mA current source.
The Series 2600B output does not exceed the compliance limit, except for the compliance limit
conditions described in

Overheating protection

Proper ventilation is required to keep the System SourceMeter
with proper ventilation, the instrument can overheat if the ambient temperature is too high or the
System SourceMeter
over-temperature protection circuit that will turn the output off if the instrument overheats. When the
over-temperature protection circuit turns the output off, a message indicating this condition is
displayed. You cannot turn the output on until the instrument cools down.

Power equations to avoid overheating

To avoid overheating, do not operate any channel on the instrument in a manner that forces the
instrument to exceed the maximum duty cycle (DC
equation (on page 7-3) below. Factors such as the ambient temperature, quadrant of operation, and
high-power pulse levels (if applicable) affect the maximum duty cycle. Exceeding the calculated
maximum duty cycle may cause the temperature protection mechanism to engage. When this
happens, an error message displays and the instrument output is disabled until the internal
temperature of the instrument is reduced to an acceptable level.
You do not have to be concerned about overheating if the following are true:
•
The instrument is used as a power source and not a power sink.
•
The ambient temperature is ≤ 30 °C.
•
Extended operating area (EOA) pulsing is not being performed.
However, if any one of these is false, the instrument may overheat if operated in a manner that
exceeds the calculated maximum duty cycle, DC
The maximum duty cycle equation is derived from the power equation below by solving for DC
The general power equation describes how much power an instrument channel can source and sink
before the total power cannot be fully dissipated by the instrument's cooling system. This equation
incorporates all the factors that can influence the power dissipated by the instrument.
7-2
Series 2600B System SourceMeter® Instrument Reference Manual
®
instrument: V = 10 V; I
SRC
Source-measure capabilities
®
instrument is operated in sink mode for long periods. The instrument has an
= 10 mA
LIMIT
(on page 4-2).
®
instrument from overheating. Even
), which is computed using the
MAX
.
MAX
2600BS-901-01 Rev. E / January 2019
General power
.
MAX