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Section 4: Theory of operation
Series 2600B System SourceMeter® Instrument Reference Manual
4-4
2600BS-901-01 Rev. C / August 2016
General power equation
P
CS
The maximum power generated in an instrument channel that can be properly dissipated by the
instrument cooling system measured in watts. For the Series 2600B, this constant equals 56.
T
AMB
The ambient temperature of the instrument operating environment.
P
DER
= T
AMB
- 30
This factor represents the number of watts the instrument is derated when operating in environments
above 30 °C. The maximum output power of each instrument channel is reduced by 1 W per degree C
above 30 °C.
P
DER
is 0 when the ambient temperature is below 30 °C.
V
OA
The instrument output amplifier voltage. This constant can be found in the tables below.
V
P
The voltage level the 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 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 instrument channel while at the pulse level.
I
B
The current flowing through the instrument channel while at the bias level.
Maximum duty cycle equation
The following equation applies 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.
When attempting to determine the maximum duty cycle, where the off state will be 0 V or 0 A:
I
B
is 0
I
P
and V
P
are the voltage and current levels when the instrument is on
Model 2601B/2602B/2604B maximum duty cycle equation constants
Constant
100 mV range 1 V range
6 V range
40 V range
V
OA
18
18
18
55
Model 2611B/2612B/2614B/2634B/2635B/2636B maximum duty cycle equation
constants
Constant
200 mV range 2 V range
20 V range
200 V range
V
OA
40
40
40
220