AC/DC converter having power saving under 100mW

[webber]

Hi all,

I would like to built an AC/DC converter with universal input
(90~264Vac) and one 12V/2A output.

It need to having power saving under 100mW when the output loading is
40mW.

Can anypne suggest me PWM ICs which can acchieve this target...

Thansk!


Webber.

 

[Phil Allison]

"webber"

I would like to built an AC/DC converter with universal input
(90~264Vac) and one 12V/2A output.

It need to having power saving under 100mW when the output loading is
40mW.

** That is a ridiculous requirement.

Can anypne suggest me PWM ICs which can acchieve this target...

** What ever for ?



...... Phil

 

[Spehro Pefhany]

"webber"


** That is a ridiculous requirement.

I think the EPA Energy Star (tm) requirement for a nameplate 24W power
supply is more like <750mW (no load).

** What ever for ?



..... Phil

Best regards,
Spehro Pefhany

 

[Phil Allison]

"Spehro Pefhany"
"Phil Allison"

I think the EPA Energy Star (tm) requirement for a nameplate 24W power
supply is more like <750mW (no load).

** With NO load, switching oscillator drive can be stopped and consumption
reduced to some arbitrary level.

But with 40mW load, it must continue.

Getting 50% efficiency from a 24 watt, universal AC voltage, SMPS when
operating at only * 0.17 % * of rating is bizarre and near impossible.



...... Phil

 

[Martin Griffith]

Hi all,

I would like to built an AC/DC converter with universal input
(90~264Vac) and one 12V/2A output.

It need to having power saving under 100mW when the output loading is
40mW.

Can anypne suggest me PWM ICs which can acchieve this target...

Thansk!


Webber.

There might be something here, but I haven't looked at their stuff for
some time
http://www.powerint.com/


martin

 

[linnix]

"Spehro Pefhany"
"Phil Allison"



** With NO load, switching oscillator drive can be stopped and consumption
reduced to some arbitrary level.

But with 40mW load, it must continue.

Getting 50% efficiency from a 24 watt, universal AC voltage, SMPS when
operating at only * 0.17 % * of rating is bizarre and near impossible.

..... Phil

It can be done with a uC. 40mW @12V is 3.3mA, good enough to run a uC
monitor to switch off the main SMPS. But you would need a secondary
(self controlled?) SMPS to run the micro.

 

[[email protected]]

It can be done with a uC. 40mW @12V is 3.3mA, good enough to run a uC

monitor to switch off the main SMPS. But you would need a secondary
(self controlled?) SMPS to run the micro.

Another method might be to charge a capacitor and run the uC from that. Power
up the SMPS for a short period to recharge. And repeat.

Feasable?

 

[Joerg]

It can be done with a uC. 40mW @12V is 3.3mA, good enough to run a uC
monitor to switch off the main SMPS. But you would need a secondary
(self controlled?) SMPS to run the micro.

That's the trick. Essentially you almost need to build a second micro
switcher that takes over once the load drops to minimums. How fast the
big one will be able to come on line when the load surges up again is a
whole 'nother matter and that is not trivial at all.

 

[Joerg]

Another method might be to charge a capacitor and run the uC from that. Power
up the SMPS for a short period to recharge. And repeat.

Feasable?

Or in SMPS speak, burp mode? Shouold be feasible but you'd need a
post-regulator. The challenge will always be what will happen when the
load comes back with gusto.

 

[whit3rd]

I would like to built an AC/DC converter with universal input
(90~264Vac) and one 12V/2A output.

It need to having power saving under 100mW when the output loading is
40mW.

The only approach that might work, is a fleapower converter (like,
12V/100 mA) that has high efficiency at low current, and a second
converter (12V/2A) that is disabled unless the current drain
requires it. DC/DC converters intended to be paralleled have
a suitable interface that you can copy (basically, all the sense
amplifiers have external coupling to ensure load sharing).

 

[JosephKK]

It can be done with a uC. 40mW @12V is 3.3mA, good enough to run a uC
monitor to switch off the main SMPS. But you would need a secondary
(self controlled?) SMPS to run the micro.

Hmmm. can you even do a bridge rectifier under 40 mW?

 

[Joerg]

Hmmm. can you even do a bridge rectifier under 40 mW?

Done it many times. Use small diodes, not them big leaky ones