39.8.2 Reference Control
| Name: | REFCTRL |
| Offset: | 0x01 |
| Reset: | 0x00 |
| Property: | PAC Write-Protection, Enable-Protected |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| ONREFBUF | REFSEL[1:0] | ||||||||
| Access | R/W | R/W | R/W | ||||||
| Reset | 0 | 0 | 0 | ||||||
Bit 7 – ONREFBUF Reference Buffer On
Turning on the buffer increases the impedance seen on the external reference, so that the current load reduces from 5μA to 0.10μA. This needs to be matched with whatever type of reference circuit is used.
| Value | Description |
|---|---|
| 0 | Reference Buffer Off |
| 1 | Reference Buffer On |
Bits 1:0 – REFSEL[1:0] Reference Selection
These bits select the reference for the ADC.
Note: The reference buffer should be
enabled (ONREFBUF=1) when using the internal INTREF or DAC output as
reference.
| Value | Name | Description |
|---|---|---|
| 0x0 | INTREF | Internal voltage reference, supplied by the bandgap (refer to SUPC.VREF.SEL for voltage level information) |
| 0x1 | VREFB pin | External 1-5.5V |
| 0x2 | DAC output | Internal 1-5.5V |
| 0x3 | VDDANA | Supply 2.7-5.5V |