12-24 vin power supply

[roofingboom]

ltc3780 board

ok looking for suggestions on a power supply
Vin can either be one battery 12 or two baterries 24 volts so the input range is 12-24 volts
and the output must always be 12volts at 3 amps.
So i was looking at this problem and the only solution i can think of is to buck the 12-24 down to lets says 6 volts and then boost the 6 to twelve volts.

any one have a good solution to use for 12-24 vin and 12vout 3a. i do not want to use flyback cause i do not want extra cost of transformer, plus time to get wound and test. let me know if anyone has a good idea or i will just have too buck down to 6 and boost to 12

thanks

 

[aNdreiBuuu]

ltc3780 power supply

you have 2 options:
1. to use a switching regulator which permit delta=1 and a low rdson MOS switch. you can optain 11.6V from 12V at 3A...
2. the best solution is: LTC3780 (High Efficiency, Synchronous, 4-Switch Buck-Boost Controller)

h**p://www.linear.com/pc/productDetail.do?navId=H0,C1,C1003,C1042,C1116,P10090

Hope this helps,
//a

 

[IanP]

test ltc3780

I think you are on the right track ..
Use, for example, the LM2576-ADJ as the 3A buck converter but I wouldn't go as low as 6V .. This converter can happily work with 1.5V difference between Vin and Vout @ 3A load, so, I would adjust the output voltage somewhere around 9-10Vdc ..
To step the 9V voltage up you may consider another LM-series switching regulator, this time the LM2577-12 .. **broken link removed**

Regards,
IanP

 

[VVV]

ltc3780

I would go for the LTC3780, as suggested by aNdreiBuu.
This is a buck -boost chip and will allow you to obtain 12V in either case using just one inexpensive inductor. Granted, the MOSFET's are not free...

 

[gorkin]

lm2577 3a power supply

Recently I develop one Buck-Boost Power Supply for automotive environment using LTC3780 controller. For some reasons, my PCB layout was made with only two sides. Even using very large tracks with interconexion vias, my design presented a poor result with lot of noise in all signal and power tracks.

In first time, for evaluate the prototype, I supply my board with one conventional power supply at 16.0V nominal and when I turned on I hear a small noise from inductor and the audible frequency noise varied as varied the entry (between 08 to 30VDC). Checking my circuit, I suspect of inductor value, then I changed for 4.70uH (before was 7.8uH) and rising the LTC3780 controller frequency for 400kHz. The noise decreased, but other power loosing increasing like the temperature of inductor and input and output electrolyte capacitors. Then I put load (pure resistive load, 6R) and take measurement in some points, using one same scope reference (the load reference). The output voltage even was 12.3VDC, but the noise as varied the input voltage changed between 2.0 to 3.5VDC

Someone here have the same experience with this controller?

Thanks, Gorkin.