Microcontroller vs discrete component design

[Richard Mackay]

Is there an easy way to determine the pros and cons of both designs with a focus on manufacturing costs?

 

[ericgibbs]

No easy way, it depends upon the project and available resources of the manufacturer.

Do you have a specific product in mind.?

E

 

[Ian Rogers]

First there is design.... You draw up a circuit that will do what is required..

Then you build a "one" off to prove proper operation.... Mod as necessary...
Then you have a couple made... Once you have your design working as per!! Then you compromise between cost and operation....

I could build my boards 10% cheaper... But the warranty would hit the roof!! There is always a central point between the two!!

 

[Richard Mackay]

It's a fairly simple PSU with 12V battery backup.
It manages the charging and discharging of the battery.
I have built and tested the discrete version on a double sided PCB that I had made. (no SM components)
I have used a dual comparator (LM393) for voltage measurement.
Features include:
> Battery charge indication (red/green led)
> Changeover relay for mains supply/battery based on mains availability.
> Low voltage cutout to protect battery when fully discharged (with built-in hysterisys to stop relay energing when load is disconnected & battery voltage recovers).
> Battery charge current limitation to prevent overloading supply.
I have used 13 resistors, 1 preset pot, 5 capacitors, 3 diodes, 1 comparator, 1 voltage reference IC & 2 transistors.
All voltages are < 15 Vdc.

 

[Nigel Goodwin]

It could obviously be simplified and made cheaper by using a micro-controller, but the main advantage would be the easy (and cheap) ability to add lot's of extra functionality.

If you don't want extra functionality, then I'd suggest staying with the comparator

 

[ronv]

It's a fairly simple PSU with 12V battery backup.
It manages the charging and discharging of the battery.
I have built and tested the discrete version on a double sided PCB that I had made. (no SM components)
I have used a dual comparator (LM393) for voltage measurement.
Features include:
> Battery charge indication (red/green led)
> Changeover relay for mains supply/battery based on mains availability.
> Low voltage cutout to protect battery when fully discharged (with built-in hysterisys to stop relay energing when load is disconnected & battery voltage recovers).
> Battery charge current limitation to prevent overloading supply.
I have used 13 resistors, 1 preset pot, 5 capacitors, 3 diodes, 1 comparator, 1 voltage reference IC & 2 transistors.
All voltages are < 15 Vdc.

A little hard to say without a schematic, but in essence you are thinking of replacing the comparator with a micro - maybe eliminate a transistor and a couple resistors. Probably not a good bet especially if you need a regulator for the micro.

 

[Mikebits]

One way to reduce cost is to not use thru-holes, as each hole adds to PCB cost. SMT would lower PCB cost.