Multiple output power supplies

[jnnewton]

Hello,
I have a project where i currently have 3 pcb's and they all have their own 12V and 5V SMPS running from 24Vdc connection to all, built using National's simple switcher. Now i have the need to generate a +/- 10V analog signal using a 0-5vdc ouput from the uC from one board which will require a minimum of +/- 10 Vdc if i use a rail to rail op amp but would prefer 12V (head room), and power a 3 V ic on another. I am almost out of room on the pcbs and was wondering what the best way to get the added voltages was. to summarize, i need:

Board 1: 12 V, 1.5A, 5 V .5 A
Board 2: 5V .5A, 3V .5A
Board 3: 5V .5A, +/-12 V .5A

Tried nationals Webbench, they seem to use all custom transformers, which i do not even want to mess with. (I like digikey!!!)

 

[mvs sarma]

Hello,
I have a project where i currently have 3 pcb's and they all have their own 12V and 5V SMPS running from 24Vdc connection to all, built using National's simple switcher. Now i have the need to generate a +/- 10V analog signal using a 0-5vdc ouput from the uC from one board which will require a minimum of +/- 10 Vdc if i use a rail to rail op amp but would prefer 12V (head room), and power a 3 V ic on another. I am almost out of room on the pcbs and was wondering what the best way to get the added voltages was. to summarize, i need:

Board 1: 12 V, 1.5A, 5 V .5 A
Board 2: 5V .5A, 3V .5A
Board 3: 5V .5A, +/-12 V .5A

Tried nationals Webbench, they seem to use all custom transformers, which i do not even want to mess with. (I like digikey!!!)

From Board 1, if you tap the ac output and put a diode and filter , you can still get -ve voltage, and this can be regulated to -12V.
Now you can use +/-12 V from this power supply and amplify the analog signal derived from your micro-controller, with a suitable Opamp with required slue rate. the gain can be adjusted to get -/+10V signal at the output.

Finally the addition is not much compared to the advantage of deriving -12V.

 

[mneary]

Tried nationals Webbench, they seem to use all custom transformers,

Try again; are you logged in? I see an inductor listed for every design I try, normally with 10 alternate suggestions.