A1. Roband was founded in 1956 and remains the pre-eminent specialist power supply company. Roband is totally independent and as a result is completely focused on providing the best possible products and services. It is never distracted by the demands of a remote board of directors, often overseas, more concerned with satisfying 'investors aspirations' than keeping its own client base satisfied. The quality of our products and services is paramount to us, our good name is all-important. We are BS EN 9100 accredited and virtually self sufficient throughout, we can simultaneously allocate priority and maintain quality.

A2. Take advantage of our experience to determine the best approach. Advise us of your basic parameters, such as input, output voltage and currents, size, cooling, interconnection method and general environment. Feel free to talk to us using the contact numbers shown or if more convenient use the contact Roband here.

A3. Although apparently not as fashionable as switch mode systems, linear units have qualities which should not be overlooked
Linear For: Simpler and electrically quiet so excellent EMC, ripple and noise performance and very fast transient response. It is often thought that switch mode units are much more efficient than linear units but as output voltages increase linear systems improve substantially in this respect.
Linear Against:: Bigger, heavier, less efficient (usually) and can only operate successfully over a limited input range without dissipating excess amounts of power. In practical sizes it is virtually impossible to maintain full compliance during extended duration transients, surges and drop outs.
Switch Mode For: Operate over a very wide input range. These units are generally rather smaller and lighter and usually more efficient. Maintaining performance during temporary loss of input is a practical proposition
Switch Mode Against: Like for like these units are more complex and electrically noisier than linear types.

A4. Efficiency as a power supply parameter is often misleading. What is of most concern is ensuring that the components within the power supply remain within safe operating limits. What the user needs to consider is a) the overall power consumption and whether the power supply is adequately cooled and b) whether there is a sufficient capacity in the source. To achieve maximum efficiency will normally mean running at slower switching frequency, and that implies a larger unit, and space is invariably at a premium.

For environmental reasons in recent years there has been a great push for lower power dissipation. There are a variety of things we can do to improve performance but in order for us to properly assist it will always be an advantage for the user to advise us of as much detail of their application. In this way we can optimise our units.

A5. Like efficiency in Q4, the effect of switching frequency is often misunderstood. It is sometimes suggested that just by increasing switching frequency there will inevitably be an attendant reduction in size. This is not so. Theoretically filter sizes reduce with frequency but at the same time other losses increase and parasitic effects become more significant. Another consideration is that like for like design a slower frequency will usually mean a more efficient (cooler) unit. There is a very real trade off between size, performance and complexity. What frequency to choose is a matter of application. We try to operate at the optimum which is often less than the maximum possible. When critical (e.g. communication and display systems) we will try to avoid particular specified frequencies. When appropriate we will synchronise to user clocks.)

A6. The $64,000 question. The answer depends on the complexity of the unit and what type of qualification (type approval) programme is required. Component lead time has an effect. Typically for a complex multi-rail design it is unlikely that a good quality A model will be available in less than 6 months. Given a well defined specification, a fully qualified unit should be available in between 9 and 12 months. Integration and other external system issues may affect the time scales. Faster times are possible but may involve increased risk.

At Roband, we will try to agree a realistic programme and highlight any risk areas. Once agreed we will do all we can to ensure that we are successful and that long-term integrity is maintained.

A7. Yes, we have a stable full time experienced design and support team and extensive in-house test facilities. This includes our own screened room for EMC, thermal cycling chambers and vibration platforms. Testing and build control are in accordance with recognised and established standards and procedures, all work is carried out in accordance with our BS EN 9100 quality control system.

A8. All units designed and manufactured in strict accordance with company guidelines and written processes and procedures. We prove by test and analysis that our design the agreed specification. We support the integration of our unit into the Purchaser's equipment and ensure that this is completed successfully. The units are built, tested, ESS/Burnt-In and inspected to a proved production data package. All activities are under the continuous scrutiny of our autonomous QA department, all work is carried out in accordance with our BS EN 9100 quality control system.