I have problem understanding how the gatedriver below works

Do I set ref to the voltage I want to retain on the output ?

Input is only for turn on the gatedriver

http://www.fairchildsemi.com/ds/FA/FAN3111C.pdf

 

The datasheet reads:

For use with low-voltage controllers and other input signal sources that operate from a lower supply voltage than the driver, that supply voltage may also be used as the reference for the input thresholds for the FAN3111E. The driver has a single, non-inverting, low-voltage input plus a DC input VXREF for an external reference voltage in the range of 2 to 5V.

And at specs:

Inputs (FAN3111E)
VIL_E IN Logic, Low-Voltage Threshold min 25, typ 30 %VXREF
VIH_E IN Logic, High-Voltage Threshold typ 50, max 60 %VXREF

 

AdrianN: "DC input VXREF for an external reference voltage in the range of 2 to 5V"

Is VXREF for setting the referens on the output from the Fan3111

 

I don't understand the question. VXREF is for setting the thresholds in the input of FAN3111E. Say you have a circuit powered at 3.3V connected to the input of the 3111. In that case you connect the 3.3V supply of the previous circuit to VXREF. That way you will be sure that the input of VXREF will be triggered correctly, so that you will have pulses at the 3111 output.

 

AdrianN: Ok I have get it totally wrong thank you for the input.

How do I know what the fan3111 sends out then when the output is set to high I mean what voltage vill it give on the output pin ?

 

AdrianN: Ok I have get it totally wrong thank you for the input.

How do I know what the fan3111 sends out then when the output is set to high I mean what voltage vill it give on the output pin ?

Visit fairchild's website and find the application notes for MOSFET drivers. Usually MOSFET drivers raise the gate voltage 15V above the source voltage. This means a Vgs of 15V.

 

libbresse: This is an on/off circuit. A low-side MOSFET driver. When on, the output will go to VDD. When off, will go to close to zero. Figure 35 shows the output driver. Figures 36 and 37 show the connection to the external MOSFET. Maybe you thought this drives the MOSFET in the active region. It does not. Again, it is an on/off driver.