14
Ripple and Noise
The ripple and noise figures stated in the datasheet are defined based on a standard measuring method. To obtain the same
results the same test setup must be used and care must be taken to eliminate any parasitic noise pickup. The diagram below
shows details of the setup and also sources of noise pickup.
Over Temperature Protection (OTP)
Each output module is protected against excessive temperatures. In the event of the internal temperatures exceeding safe
levels the entire correspondent section may be latched off. To resume operation of the power unit, disconnect the AC input
voltage for 2 minutes, ensure external ambient temperatures are within specifications and then reconnect the AC input
voltage. Note that no warning is given on both the AC_OK signal for faults of this type.
Transient Response
The RCB1200 output modules have been especially designed to have high reliability, and to achieve this all electrolytic
capacitors have been eliminated from the design. Due to this, high dynamic load transients can cause relatively high voltage
deviations at the output and although the outputs have a very high loop bandwidth with typical recovery times of less than
100 µs, the voltage deviations may still be excessive for some applications.
An example application is detailed in the diagram below and shows typical responses at the terminals of the output module
and at the load. Notice that the voltage deviation due to cable inductance exceeds the module response and hence a capacitor
located at the module terminals will have little effect at the load. The optimum solution is to locate a low impedance
electrolytic capacitor at the load which will eliminate the inductive cable drop and also reduce the typical voltage deviation at
the module.
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