Power Supply And Thermal Considerations - Stanford Research Systems SIM954 Operation And Service Manual

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2.6 Power Supply and Thermal Considerations

A SIM954 module can initially draw up to 750 mA of power supply
current from both 15 V rails of the SIM900 mainframe. It is therefore
recommended that you limit the number of SIM954 modules to four
per mainframe to stay within the 3 A power supply limits.
If two or more modules are used in one mainframe, they should not
be placed in adjacent slots, and SIM954s should not be placed next to
temperature sensitive modules like the SIM928 or SIM965. A SIM954
can degrade the temperature drift of other SIM modules, and care
should be taken to avoid such configurations in applications that rely
on the precision of the SIM system.
These amplifiers can generate more heat by design than a single wide
module can conduct to the mainframe. In the worst case, a SIM954
can dissipate close to 25 W of power. However, since the internal
power supply circuit has a negative thermal feedback, the module
will quickly reduce the power consumption to 15 W by limiting the
supply current to about 500 mA.
The main cooling mechanism of the module is conductive and the
heat will flow towards the front panel which will get noticably warm
(up to 50 C or 130 F) for a module operated in a 25 C environment.
Higher environmental temperatures can lead to thermal shutdown
of the op-amps and highly distorted signal waveforms in modules
which are driven to their full power limits. The thermal shutdown
is reversible and will not lead to longterm damage of the operational
amplifiers. However, the built–in electrolytic decoupling capacitors
will degrade if the module's internal temperature is near or above
50 C for hundreds or thousands of hours.
Temperatures on the front–panel BNCs that are uncomfortable to the
touch are a good indicator that the module is being used above its
long–term power handling capability.
SIM954 300 MHz Dual Inverting Driver Amplifier
General properties