help in IC for switching from main power to backup power

[gunbladespecialist]

Hello guys i have a problem right now..
We are currently designing a system that will have a main power source as well as a backup power source.
Once the main power source runs out, the systemwill the  switch to the backup source. I was wondering if I can implement this
using an IC or a relay. I hope you could help me out. thanks..

P.S. the two power supplies are both DC..

[ahlburuto]

Kung relay logic, ang mga kelangan mo eh dalawa na magnetic contactor, yung isa eh para sa main supply tpos yung isa eh sa standby supply. 2 relay na 4pdt or 2pdt. yung isang relay eh connected yung coil nya sa main supply. At sya ang magpower up ng isang contactor. tapos yung isang relay naman eh para sa isang contactor. kelangan mo dito ng UPS kahit yung maliit lang at timer para sa switching ng mga contactor. UPS will serve sa switching ng standby power.

br

[gunbladespecialist]

portability is one of the top priority sa design..kaya po naghahanap me ng IC that will do the switching job between the two dc supplies which is 6V

[ahlburuto]

Alin yung 6volts? yung control voltage? at para sa 220vac supply ba ito or demo lang na ang gagamiting supply eh 6volts?

[ahlburuto]

both power supply ba eh 6volts?

[gunbladespecialist]

yan po ang supply voltage...bale the 6v will be distributed to the different components via a buck converter and each of the power supplies are rated 6V..pero isa lang ang normally active while the other one will be on standby and pag naubos na ang main power that's the time magiging active ang standby.

[ahlburuto]

anung mag trigger sa standby power? lagi ba syang naka on or mag on lang yung standby power pag nawala na yung main power? Or both supplies ar at on position?

[gunbladespecialist]

yan dn po ang tinatanong ko..hehe.. the one that will trigger the standby power once nag run out na ang main.. possible kaya cya using an IC.. if so anong IC ang ggmitin?

[ahlburuto]

kaya yan ng relay logic. iparallel mu lang yung switch ng standby power supply sa relay ng main supply. dun sa normally close mu sya parallel. kasi pag naka energized yun eh normally open mangyari dun... di pa ko nakapaggawa nyan using mga IC eh. intayin mong magising yung iba nating mga kasama. baka me idea sila sa kelangan mo.

sa aking design eh puro relay lang gamitin mo. kelangan mu lang ng electrical interlock nun para safe sa switching....

br

[gunbladespecialist]

noted po sir.. ty po.. ano pong type ng relay ang gagamitin? sorry po if im asking too much.eto po kasi task ko sa OJT e and hindi pa ako nka pag implement nga circuit using relays..based on assumptions and theories lang tlaga yung akin.. it would help sana if merong block diagram...im also searching on google about relays

[RiDdLeR???]

Pareho bang battery ang main and backup power supply?

[1110000]

depende yung relay mo sa load ilang watts ba yung load mo?

[zer0w1ng]

2 diodes will do.
But the primary supply should be a bit more voltage than the secondary, so that there will be no consumption on the secondary ps.

[1110000]

@ zer0w1ng
diba pede naman  pagibahin yung voltage nila using diode again

[gunbladespecialist]

regarding the diodes?ano yung configuration nla?will the two be forward biased?

[ahlburuto]

noted po sir.. ty po.. ano pong type ng relay ang gagamitin? sorry po if im asking too much.eto po kasi task ko sa OJT e and hindi pa ako nka pag implement nga circuit using relays..based on assumptions and theories lang tlaga yung akin.. it would help sana if merong block diagram...im also searching on google about relays

kung 6volts ang voltage na gamitin o eh merong nabibili na pcb mount na 6vdc na relay, anu nga lang yun 1PDT. kaya madami kang magagamit. depende rin kung ilang contact ang kelangan mu.

[zer0w1ng]

regarding the diodes?ano yung configuration nla?will the two be forward biased?

Like this:

Code: [Select]

Primary (6.71V)  o---------|>|------+------o Output (6V)
                                     |
                                     |
 Secondary (6.7V) o---------|>|------+


@ zer0w1ng
diba pede naman  pagibahin yung voltage nila using diode again

You could put another diode to drop the voltage. But this depends on the application.

[gunbladespecialist]

@zerow1ng

correc me if im wrong, pero based dun sa diode config..pero it looks like that both pwer sources are working/drawing power at the same time?

['yus]

Or, you can use two ORing mosfet instead of forward diodes..


advantages:
1) higher current capability (provided that you use power fets with low "on-resistance"),
  and also, no need to increase the output voltages of the two supplies..
2) smaller compared to mechanical relays (if you use mosfets with small packages like "power so-8")
disadvantage:
1) additional circuit (and also bias voltage) for turning-on the two ORing fets..

[rdpzycho]

ang tawag sa IC na yan ay Power Multiplexer. gumagamit ang mga handheld devices na battery powered nito to switch from external supply or internal battery, or from 2 batteries.

eto lang naaalala ko pero 5.5V lang ang max voltage niya. nababago yung mga threshold kung kailan lilipat. maliit na IC 'to. TSSOP package. no need for external logic. trimmer na lang ang external circuit para i-program yung thresholds. tapos mga capacitors na lang. it takes around 1" x 1" footprint kung kasama na yung mga trimmer at capacitors.

Dual In/Single Out Autoswitching Power MUX, Manual/Auto Sw, Adj. Cur Limit, Adj. Vol Threshold

http://focus.ti.com/docs/prod/folders/print/tps2110.html