4-4
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2600AS-901-01 Rev. B / September 2008
Section 4: Source-Measure Concepts
Series 2600A System SourceMeter® Instruments Reference Manual
General SourceMeter instrument power equation
P
CS
= The maximum power generated in a SourceMeter instrument channel that can be properly
dissipated by the SourceMeter instrument cooling system.
T
AMB
= The ambient temperature of the SourceMeter instrument operating environment.
P
DER
= T
AMB
- 30
•
This factor represents the number of watts the SourceMeter instrument is de-rated
when operating in environments above 30°C. This is represented as a temperature
because the maximum output power of each SourceMeter instrument channel is
reduced by 1W per degree C above 30°C.
•
P
DER
is 0 when the ambient temperature is below 30°C.
V
OA
= The SourceMeter instrument output amplifier voltage. This constant can be found in the
tables below.
V
P
= The voltage level the SourceMeter instrument is attempting to force while at the pulse level.
•
When operating in quadrants 1 or 3 (sourcing power), the sign of this voltage must
be
positive
when used in the power equations.
•
When operating in quadrants 2 or 4 (sinking power), the sign of this voltage must be
negative
when used in the power equations.
V
B
= The voltage level the SourceMeter instrument is attempting to force while at the bias level.
•
When operating in quadrants 1 or 3 (sourcing power), the sign of this voltage must
be
positive
when used in the power equations.
•
When operating in quadrants 2 or 4 (sinking power), the sign of this voltage must be
negative
when used in the power equations.
I
P
= The current flowing through the SourceMeter instrument channel while at the pulse level.
I
B
= The current flowing through the SourceMeter instrument channel while at the bias level.
Maximum duty cycle equation
1
NOTE When attempting to determine the maximum duty cycle where the off
state will be 0V or 0A:
•
I
B
is 0
•
I
P
and V
P
are the voltage and current levels when the
SourceMeter instrument is on.
1. Equations apply to both channels, sinking or sourcing power simultaneously. If a duty cycle less than 100% is required to avoid
overheating, the maximum on time must be less than 10 seconds
V
OA
V
P
–
(
)
I
P
( )
DC
MAX
V
OA
V
B
–
(
)
I
B
( )
P
CS
P
DER
–
(
)
≤
+
DC
MAX
P
CS
P
DER
–
(
)
V
OA
V
B
–
(
)
V
B
(
)
–
V
OA
V
P
–
(
)
I
P
( )
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100
×
2
≤