FAQ’s

Some great questions and answers about Bias and Cita products.

How is a Bias constant-power module different from other switching power supplies?

  1. There are very few AC/DC switching power supplies available in the 0.5, 1, 2 and 4 watt power ratings.
  2. There are no competing designs of these power ratings and physical size which are isolated.
  3. There are no competing designs of these power ratings and physical size which do not need external filtering to meet EMC/EMI Class B specifications.

Why do you say that a Bias constant-power module does not require any external filtering?

Bias products incorporate a proprietary technology which greatly reduces the generation of EMI. The levels achieved are within the limits specified in FCC Part 15 and EN 55022, Class B.

I have always used an external power supply to avoid UL approvals of our products. How would an internal Bias constant-power module help in this process?

All Bias modules are EN/UL Component Recognized to 60950-1 (2nd Ed.) and a CB report is available. Contact us for more details.

We’ve always designed our own low-power supplies on-board. Why should I consider using a Bias constant-power module instead?

A variety of considerations are appropriate.

  1. The module is complete, you need not invest any time in design so you can spend more time designing product features valuable to your customers.
  2. Unmatched for wireless & M2M applications for combined size/EMI/RF/no load efficiency.
  3. No current limit + constant power = 0% de-rating. You get 100% full power from -40°C to +85°C.
  4. If your designs are space constrained, no other technically comparable solutions are as small.
  5. Bias modules have an application flexibility difficult to achieve with other designs. Contact Bias for details.
  6. Instead of needing to source a variety of components and maintaining inventory on each, you can deal with just one module.
  7. Bias products are EN/UL Component Recognized (see above) simplifying your process.

I have a low-power application requiring peak power that is more than four watts. Will a Bias supply work?

Yes! There are two approaches.

  1. Bias supplies can easily handle highly capacitive loads. Adding capacitance on the output may be capable of providing the peak power required.
  2. Bias supplies can be connected in parallel without additional circuitry. Simple parallel or N+X designs can be accomplished.

The power supply that I’m working with now takes forever to charge a supercapacitor. Will the Bias Power module be any different?

Yes. Bias Power modules accept a capacitive load. As a result, they can charge a high-value super capacitor much faster than most other switching power supplies. This can be very important when keeping a supercap charged for backup/shutdown applications.

For low-power applications, I’ve always used simple linear power supplies. Why should I consider switchers like the Bias modules?

Efficiency, Efficiency, Efficiency!

Can I run two Bias power supplies in parallel?

Yes, and without any load-sharing circuitry or droop resistors.

I’m a bit confused about exactly what is coming out of the multiple outputs on some of your supplies. Can you explain?

All Bias constant-power modules provide a primary DC (Vo) output. This output, while well regulated at either 8, 12, 14 or 24VDC develops ripple at either 100Hz or 120Hz as load is increased. In many applications, this ripple is acceptable because it is never used directly; it provides a DC ‘bus’ that is further regulated downstream to generate the very low voltages required to power logic IC’s. For some applications, like driving analog IC’s or relays, some smoothing may be required. External capacitors can provide a reduction in this ripple, as can the use of a linear regulator. For our dual output supplies with part numbers ending in -33 or -50, Bias uses an internal linear regulator to provide a secondary (Vr) output. The input to this regulator is the above mentioned primary VDC supply.

The instrument I’m designing will be used worldwide with different line voltages and frequencies. What should I know about how a Bias constant-power module will work in this situation?

Bias supplies are designed to operate at standard 50Hz and 60Hz line voltages from 85 VAC to 265 VAC. Specific performance specifications are available on the appropriate data sheet.

How is it that Bias can help me meet Energy Star requirements?

Many Energy Star requirements, and specifically those for appliances, specify standby power of 1 watt or less. Generally, this has required a significant re-design of an existing power supply. The use of the Bias module can often reduce the design time to accomplish these requirements.

My circuit design has requirements tha are somewhat different than those offered by your standard modules. Can you customize your product to meet my requirements? If so, what’s the minimum quantity?

Bias will consider custom module designs where annual quantity commitments are sufficiently large or NRE’s provided. Some special requirements may even be met with minor modifications to our module. Tell us about your needs.

I don’t see any specification for what switching frequencies you use.

Bias products use a switching frequency slightly less than 100kHz.

My department has been downsized and we really don’t have a power designer here anymore. Can you assist with applications engineering support?

Please call us with details about your specific power, space and environmental requirements.

In the past, we used an earlier generation of Bias power supplies with different pin-out configurations. Is there any way that I can match a new supply to our old boards?

Available space and some technical specification differences will determine this. The best approach is to contact Bias.