PC Power supply

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
davy_shi

What does "better performance" mean to you?
Aren't you OK with the internal voltage regulator characteristics?
For new designs you should consider a UCC equivalent (less start-up current; high oscillator frequency; mosfet base push-pull output circuit).
If you are familiar with current mode pwm controllers, you can try an active clamp topology (for high efficiency and low EMI level) and you can use UCC289x.
 
I have used the UC3842 and 3844 in smps for car and it works very well if you do it right.

Some pc power supplies uses the ic, tho in forward converter topology. Check the older compaq atx supplies with 90mm fan, but be aware that the connector pinout is different.
 
Maxiz

You might try a lightbulb as a series resistor. Try 100W, then 60W, 25W light bulbs and see if they get your computer to run off the inverter.

I understand the PC PSU is connected to the computer, right? Because the PS will not come on without the expected PC load attached to it.

Florin is right, SMPS's have large bulk capacitors, just after the bridge rectifiers, and these present a near-zero resistance to the source in the first moments.

The car inverter, more than likely, tries to qualify the load before outputting full power, and the PC PSU is an atypical load for it. In turn, the PC tries to qualify the line power, before drawing power from it, and it's got nothing to qualify, because the inverter is hesitating to put out full power.

Sort of like two fax machines each waiting for the other to send the handshake tones.

Andy
 
A good inverter should provide inmediate overcurrent shutdown followed by a soft-start phase to overcome that issue with storage capacitors. Note that most SMPS include a NTC thermistor in series with the mains line in order to reduce inrush current.
 
Disabled Account
Joined 2005
Hi, Maxi,

I just come by.

My suggestion, use SMPS, not linear regulator. Linear regulator is only for small different Vin an Vout. If you use 12V to 5V linear, wow... lot of heat mean loss of power and loss of lifetime.

In my country there are ready made car SMPS. I can get any secondary voltage by just add new winding and rectift it. Some of them have protection at primary side. No matter your winding. Most are toroid, very easy to add new winding. Remember! Use fast diode, not usual diode.

Remember also that you can not get negative supply from one battery source with linear regulator. Then SMPS is a must.

br/tn
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.