How much current can KV11Z P5V_USB safely output?

[jefflfree]

I wanted to connect multiple sensors to the KV11Z board. How much current can it source (I am trying to decide whether to use the P5V_USB pin or a direct connect to battery to power the sensors.

[Sabina_Bruce · Accepted solution]

Hi Jeff,

The P5V_USB is used to power the K20 in the evaluation boards for the KV11z. Both the FRDM-KV11Z as well as the TWR-KV11Z75M use the K20 as its OpenSDA microcontroller. OpenSDA is a serial and debug adapter that is built into several NXP evaluation boards. It provides a bridge between your computer (or other USB hosts) and the embedded target processor( in this case the KV11Z). 

In your case if you'd like to use this same line to power your sensors you may but you have to consider the USB VREG specification in section 6.8.3 for the Kinetis K20, to make sure you it doesn't affect its behavior. 

I'd suggest to measure how much current your sensors consume and see if it will impact this negatively in any way, if so then you should use an external battery.

Let me know if you have any other questions, I'll be glad to help out.

Best Regards,

Sabina