AC to DC Universal Power Supply

Yunus,

Can you give more details on your specification? I assume that the output must be isolated?

What is the output voltage and power level?

What is the tolerance on the 24 V ac input, i.e. what is the minimum value?


For sure, if a single design is done to cover the full range of input voltage, the performance will be compromised compared to 2 separate design.


I did a search of available TI Designs and reference designs (you can do a search by power parameters here: www.ti.com/.../refdesignsearchresults.tsp), for an isolated output, with AC input for 24-240 V range, and 1 existing solution was found:
www.ti.com/.../PMP10098

This is designed to work over 19 - 265 V input, with 12 V out at 0.5 W - so it is very low power.

If you need higher output power, a single wide-range design will be challenging.


Thanks,
Bernard

Hi Bernard,

Thanks for your reply.

Sorry for my delayed response.

Below are the requirements :

- Input Supply : Min 24 VAC to 240 VAC.

- Tolerance on 24 VAC : Min = 16 VAC , Max = 265 VAC

- Output Voltage : 24 VAC , +15 VDC or +17 VDC.

- Power Rating : 20 VA to 22 VA 

24 VAC output supply for external sensors & actuator drive & it should source minimum 0.5A & maximum peak 0.8A as a load current.

+15VDC or +17VDC is for digital circuits.

Please suggest some solution.

Thanks 

Yunus

Yunus

When you say that the main output is 24 V AC, is this @ 50/60 Hz? Why is AC output required?

This will require a 50/60-Hz mains isolation transformer, which will be large, heavy and will have very low efficiency.


Can you clarify your system block diagram?


Thanks,
Bernard

Hi Bernard,

24VAC is utility power for actuator supply & it should be 50Hz.

Please see below block diagram - 

Regards,

Yunus

Yunus

This is a much more challenging task than it might seem.

Does the 24 V AC output need to be isolated or not? The 24 V AC is most commonly achieved with a simple 50-Hz mains isolation transformer, with a suitable step-down ratio (for either 110-V or 240-V input). But these are bulky and lossy. Moreover, if it needs to operate from either 24-V AC input, or 110-V or 230-V, this requires 2 different step-down ratios, or no step-down at all for 24 V AC input. It’s just not possible to implement with the same transformer.


The only way to get a regulated/controlled 24 V AC output from a variable DC input would be to use an inverter to generate the AC output – but it would need to operate over a very wide range, and would add a lot of complexity and cost.


Unfortunately, I cannot find any TI-Designs or reference designs that generate a 24 V AC output.


Thanks,
Bernard