Accurately measuring output noise and ripple requires a basic understanding of the high frequency nature of noise. Very often, noise (as commonly measured) is actually the vector sum of common and differential mode noise . .

Paralleling of the HDM Series DC-DC Converters for increased power output is accomplished by connecting the inputs and outputs in parallel, with one additional connection made between the parallel control pins as well. The connection between parallel control pins forces the modules to share the load current within a few percent . . .

The synchronization option allows operation of HDM modules to operate at a customer-selected frequency within the limits of the following table. When no sync signal is provided, the module will operate at a nominal switching frequency of 300kHz. The external synchronization circuit can have either a high or low impedance from SYNC to -IN when inoperative without disturbing the free running frequency of the module . . .

The remote sense feature provides excellent regulation at the load rather than at the HDM module output terminals. It does this by sensing the voltage at the load, compensating for load current IR drops across output connectors, printed wiring traces and distribution cables, as well as applicable oring diode forward voltage drops . . .

Output voltage trimming allows the user to make small changes, either increasing or decreasing the output voltage. This is useful when compensating for distribution and connector voltage drops so that the voltage is as required at the load. It is also helpful when checking the system for proper operation at the extremes of the output voltage tolerance range (often called voltage margining) . . .

Line regulation is the HDM DC-DC converters ability to maintain a constant output voltage as the line (input) voltage changes. Load regulation is the module's ability to maintain a constant output voltage as the load current changes. Line and load regulation are two of the most common types of power supply measurements. Although straightforward, there are some simple guidelines that will help ensure accurate readings.

The logic on-off function allows the user to inhibit the output of the HDM module using a simple TTL logic signal or mechanical switch, and avoids having to turn off the DC input bus. This feature is useful for controlling the output power without having to cycle the input power. It is particularly useful for the HDM 300 Series, where it avoids recharging of the input energy storage capacitors that normally filter the 300 VDC bus voltage.

The Rantec HDA Series single-phase AC active power factor correction unit permits operation of the Rantec HDM 270V Series of DC-DC Modules from a standard single phase AC power source. In addition to accepting a wide range of input voltages, the HDA Series offers the benefit of active Power Factor Correction (PFC) and has models for either 60 or 400 hertz operation.

This application note provides information for implementation and use of mating sockets with Rantec’s HDM DC-DC converter modules. The use of mating sockets in an interface printed wiring board (PWB), rather than soldering, may improve system production and repair times, while maintaining compliance with military standards (MIL-STD). Using a system PWB interface is the preferred electrical and mechanical approach for the HDM modules, resulting in superior reliability, predictable ripple and noise results, and ease of assembly.