The Voltage Reference (VREF) is a device that produces a fixed (constant) voltage, providing references to the analog comparators and external circuitry. The voltages include /2, /3 and /4 dividers of the VDD power supply as well as external sources. The macrocell also has an option to output reference voltages on PIN 18 and 19.

Parameters

Force bandgap on:

This parameter keeps the Bandgap on while the chip is powered.

Output active buffer:

This parameter enables the active output buffer on VREF0 and VREF1 outputs.

Source Selector:

The Vref output pin will slave its output from the input to the selected analog block. The output reference can be changed from the sources’ properties window.

Output:

• PIN18: is only for VREF1;

• PIN19: is only for VREF0;

Table 1.

VDD	Practical VREF range
1.7V-5.5V	50mV ~1.2V