AD7293 EVAL board

Hello everyone,

I have the EVAL-AD7293SDZ board which is the evaluation board for amplifier current controller.

The eval board itself provides  internally 5V for the drain voltage, I want to externally supply 28V .

But my question arises here! in the datasheet (page 29) this is written:

" FOR DRAIN VOLTAGES HIGHER THAN 20V IT IS RECOMMENDED
TO TIE PAVDD TO VDD AND SCALE THE CONTROL SIGNAL EXTERNALLY.
 "

what does it mean by tie up?? and what does scale the control signal externally implies??

I would appreciate if anyone can guide me.

Regards,

SaraPDF

  • HI Sarah,

    Tie up means connect PAVDD to the same voltage as the voltage on the drain which in case will be 28V. Scale the control signal externally means if you are using the PA_ON pin the VGS of the external PMOS fet when PA_ON is "on" (0V) will now be 28V. You will need to scale this down depending on the specifications of the external PMOS fet.

    Valerie