0

A computer SMPS is capable of providing stable power supply to multiple devices like hard drive, CD/DVD drive, etc....

Is it possible to convert an old SMPS to power a tablet/cellphone?

What modification should I do an SMPS to serve 3.1 AMP 5.0 volt to charge 7200 mAh 10 inch tablet device?

I would like to convert a 450W PC ATX computer power supply with an input voltage of 5 AMP 230 volt, the output I want is 3.1 amp 5.0 volt which can be connected to a cellphone or tablet with a 2.0 mm DC pin

The IC which I see inside is WT7520.

I can see the high power components F12C200, D13007k, C5027-R attached with heat sink.

The label sticker provides the following input/output:

INPUT:  AC230V 3.5A 50Hz
OUTPUT: AC230V 1.5A 50Hz

But I don't know what is the current provided to hard disk power plug.

Ricardo
  • 6,134
  • 19
  • 52
  • 85
Dickens A S
  • 101
  • 4
  • We would need to know *which* SMPS module you're wantong to convert, what controller IC it uses, and what its current input/output voltages are, as a very minimum for being able to answer this question. – Robherc KV5ROB Mar 09 '16 at 05:59
  • 1
    Read your ATX PSU label carefully. You'll find that it outputs 5V @ a large number of amps, and you need 5V @ 3.1A. This might be closed as a duplicate of [this question](https://electronics.stackexchange.com/questions/34745/choosing-power-supply-how-to-get-the-voltage-and-current-ratings) unless you narrow your question down. Also keep in mind that most ATX PSUs have a minimum load. – uint128_t Mar 09 '16 at 06:10

1 Answers1

1

Any Smps with well regulated 5V DC can be used as a charger. But there must be some sort of safety/ protection be in place so that the output current is limited.

A standard mobile or tablet nay demand 2Amps of charging current from a 5V smps. A standard ATX power supply may capable of delivering 25A on its DC 5V output. Designated chargers will have internal current limit to avoid excessive current flow during malfunction of the connected gadget. But having these gadgets connected to an ATX will reduce the gadget to ugly burnt thingy in case of malfunction of the battery/ charger controller. Safety is thus seriously jeopardize.

So, what can be done is build a simple current limiter and install it between the SMPS and yr gadget.

current limiter circuit

Current sense resistor of 0.33ohm will turn on the Q2 at about 2Amps and the base bias for Q1 will be removed thus limiting the current at that value.

Q1 must be rated at least two times of the intended charging current and it must be on the heatsink.

soosai steven
  • 1,695
  • 1
  • 11
  • 16
  • That will not work. Voltage drop 0,6V from Q1 base to Q1 emitter is unacceptable for usb. better idea is to have fuses( or polyfuses ) on positive coming to eaach port – Volodymyr Kalinyak Jul 02 '19 at 20:31