Using a single PWM Controller for 2 Voltage ?

[ayeong]

Hi,

I have an incoming voltage of 9V. Is it possible that I used a single PWM controller to output either +5.0V or +3.3V but not both together ?

Thanks

Cheers,

 

[bobcat1]

Hi

First you can use linear regulator to drop the 5v into 3.3 V

2nd you can use sepic topology converter with a 2 loop transformer e.g

the transformer have 2 secondry coils use the first (5V) to close the loop
and the 2nd for the 3.3 V

Enjoy

Bobi

 

[Cluricaun]

Hi

Take a look at Maxim, ie MAX50x5. Start here:
h//p://para.maxim-ic.com/ss.asp?Fam=DCDC_All&Tree=PowerSupplies&HP=PowerSupplies.cfm&ln=

There are many others like On-Semi ...
Depends of price and size what you need, perhaps bobcats solution is cheaper, it depends on the rest of the design.

//=tt

Cluricaun

 

[ayeong]

Thanks for the reply.

I have seen a controller from Maxim (MAX1626) which is very attractive & neat in switching between 3.3V/5V.
**broken link removed**

However, it looks expensive from a manufacturing point. Thus, I'm wondering anybody manage to do that cheaply using discretes ?

An LDO doesn't seems to be suitable for high current and huge difference in input & output voltage due to heat dissipation. For example, (9V-5V)*2A & (9V-3.3V)*2A.

Thanks

Cheers,