Frequently Asked Questions

Why Roband?
How do I decide what type of power supply I need?
Linear or Switch Mode?
Efficiency?
What is the switching frequency of a Roband SMPS?
How long will it take to develop a power supply from scratch?
Can Roband ensure compliance?
How do you ensure reliability?


Why Roband?
Roband is the pre-eminent specialist power supply company with over 40 years of experience. The quality of our products and services is paramount, our good name is all-important. We are BS EN ISO 90001 accredited and virtually self sufficient, we can simultaneously allocate priority and maintain quality.

How do I decide what type of power supply I need?
Take advantage of our experience to determine the best approach. Advise us of your basic parameters, such as input, output voltage and currents, size and general environment. Just call us at the contact numbers or use the unique enquiry form.

Linear or Switch Mode
Although not fashionable, linear units have qualities which should not be overlooked.
Linear For: Simpler and electrically quiet for EMC and noise performance. As voltages increase linear systems become suprisingly efficient.
Linear Against: Bigger, heavier, less efficient (usually) and can only operate from a limited input range; it is virtually impossible to maintain full compliance during the extended duration transients and surges called for in military specifications. However our units are designed to remain safe during such circumstances. Linear units can only work from a.c.
Switch Mode For: Operate from a.c. or d.c. inputs and over a very wide input range. These units are generally much smaller and lighter. Usually more efficient.
Switch Mode Against: These units are more complex and electrically noisier than linear types.

Efficiency?
Efficiency as a power supply parameter is much discussed but often misleading. Different units have different considerations. For example a low power device will have disproportionately higher standing losses and consequently a poorer efficiency than a high power unit. What is usually of most concern is ensuring that the components within the power supply remain within safe operating limits. In a low power unit this is less likely to be a major issue. It is usually more useful to specify in terms of maximum allowable input power and unit dissipation.

What is the switching frequency of a Roband SMPS?
It is a common misconception to believe that increasing switching frequency will inevitably lead to reduced size. Losses increase with higher frequencies and there is a very real trade off between theoretical size reduction and degraded performance. We operate at the optimum frequency for a particular application, this 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.

How long will it take to develop a power supply from scratch?
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.

Can Roband ensure compliance?
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.

How do you ensure reliability?
The unit is designed and manufactured in strict accordance with company guidelines and written processes and procedures. We prove by test and analysis that our design not only meets the agreed specification but also works successfully in the user equipment. 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.