REFCTRL

Name:: REFCTRL
Offset:: 0x01
Reset:: 0x00
Access:: PAC Write-Protection, Enable-Protected

Bit7	6	5	4	3	2	1	0
ONREFBUF		REFRANGE[1:0]				REFSEL[1:0]
AccessR/W		R/W	R/W			R/W	R/W
Reset0		0	0			0	0

Bit 7 – ONREFBUF: Reference Buffer On

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 5:4 – REFRANGE[1:0]: Reference Range

Reference Range

REFRANGE[1:0]	Reference Voltage
0x0	Vref < 1.4V
0x1	1.4V < Vref < 2.4V
0x2	2.4 < Vref < 3.6V
0x3	Vref > 3.6V

Bits 1:0 – REFSEL[1:0]: Reference Selection

Reference Selection

These bits select the reference for the ADC.

Note: The reference buffer should be enabled (ONREFBUF=1) when using the internal bandgap or DAC output as reference.

Value	Name	Description
0x0	Internal bandgap	Internal 1.024V, 2.048V, 4.096V
0x1	VREFB pin	External 1-5.5V
0x2	DAC output	Internal 1-5.5V
0x3	VDDANA	Supply 2.7-5.5V