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How do I obtain 500mA from USB ?

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Shinnster

Shinnster

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Okay so my current design is basically using boost converter to convert 5V-12Vdc to power a 12Vdc component, when I test it with a PSU ... (0.5A + 5Vdc) it was working but with USB...the device was not working properly as the voltage was like 0.33V and current was 0.5A.... basically I need around 480mA...Is there any non-programmable chip to help enable the USB port to supply constant 5V and 0.5A? A solder-able chip would be great..not like MAX 8895.. **broken link removed**

Thank you :)
 

The Maximum supporatable current (Iusb Max) was 500mA. If u need more current u can cascade two USB poarts
 

sreepss said:
The Maximum supporatable current (Iusb Max) was 500mA. If u need more current u can cascade two USB poarts
Click to expand...

I know that. I want to obtain that but I can't. It only churns out 100mA. I know I need to comm with the USB to get 500mA but how do I do that without any communication device (programmable chips) ?

I just want to use USB's 5V and around 400mA, but instead, 5V and 100mA.

Any ideas what to build to fix this?

P.S my circuit is connected to a boost converter circuit (12V) to power a device.
 

I know I need to comm with the USB to get 500mA but how do I do that without any communication device (programmable chips) ?
Click to expand...
Following the USB specification strictly, you are not even allowed to consume 100 mA "without any communication". Most hosts will allow 500 mA without restrictions, some don't have exact current limit or a power switch at all, but you can't rely on it.
 

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