I want to have 5v inside my device to power otg devices.
Sorry, but you are missing the point.
There is no such thing as an *OTG Device*. The Phone itself must have the *OTG* feature.
Normal phones operate as a USB *client* ... They 'respond' to USB hosts, and the port acts as an *input* for power.
Memory sticks, USB Mice and keyboards... They are all USB *clients* as well.
Now, some phones and tablet manufacturers realize that some users want to be able to use a USB keyboard or memory sticks with the phones/tablets so they began to include a feature they call 'OTG'.
This feature *reverses* the normal behaviour of the USB port on a phone to that is acts like a USB *host*.
If you phone does not have this feature, then regardless of power or not *no* USB device will work when connected to your phone. Two USB *clients* will not directly communicate. It would be like connecting two memory sticks together assuming they would copy the contents to each other...
The phone's USB port is an *input* for power only, and the phone's USB port is a *client* or *slave* that will only respond and work properly when connected to a *host*.
You cannot simply add power, and expect the phone to magically reverse the function of the USB port.
The only possible benefit you could ever have from doing this modification, is that your phone would be able to charge the battery of other phones, or turn on the power LED of another USB device. Data will not flow!
Additionally... side-affects may include:
- Broken phone...
- Broken Radio, or intermittent radio. (Bluetooth, GPS, Cellular)
- Broken chargers.
- Broken computers...
Only sensible solution is to buy a portable USB charger/power-pack.
*If* your phone supports USB OTG, you may be able to buy a special adaptor to introduce external power to the OTG adaptor... supplying 5V by yourself if no easy task.
I strongly encourage you to abandon this project.