Problem $4$: $(15$ Points$)$ Your load is a microcontroller whose power pin needs $3\mathrm{.}3$V$,$ but you only have a $5$ V source available.$$ Design a circuit that will limit the maximum load voltage to $3\mathrm{.}3$V$.$ Load current ranges from $1$ mA in standby to $8$ mA when the microcontroller is operating.$$ The Zener needs a minimum of $500$ uA to regulate.

a$)$Design Rbias for your circuit to work correctly

b$)$State the Zener diode type number$($s$)$ you need $($from Lecture $30$ slide$)$