13.11.8.7 Voltage References System (VREF) Control

Name: VREF
Offset: 0x1C
Reset: 0x00000000
Property: PAC Write-Protection

Bit 3130292827262524 
          
Access  
Reset  
Bit 2322212019181716 
     SEL[3:0] 
Access R/WR/WR/WR/W 
Reset 0000 
Bit 15141312111098 
          
Access  
Reset  
Bit 76543210 
 ONDEMANDRUNSTDBY   VREFOETSEN  
Access R/WR/WR/WR/W 
Reset 0000 

Bits 19:16 – SEL[3:0] Voltage Reference Selection

These bits select the Voltage Reference for the ADC/SDADC.

Note:
  1. 2.0V to 2.5V can be used when the supply voltage (VDDANA) is higher than 2.7V.
ValueDescription
0x0 1.0V voltage reference typical value
0x1 1.1V voltage reference typical value
0x2 1.2V voltage reference typical value
0x3 1.25V voltage reference typical value
0x4 2.0V voltage reference typical value
0x5 2.2V voltage reference typical value
0x6 2.4V voltage reference typical value
0x7 2.5V voltage reference typical value
Others Reserved

Bit 7 – ONDEMAND On Demand Control

The On Demand operation mode allows for enabling or disabling the voltage reference depending on the peripheral requests.

ValueDescription
0 The voltage reference is always on, if enabled.
1 The voltage reference is enabled when a peripheral is requesting it. The voltage reference is disabled if no peripheral is requesting it.

Bit 6 – RUNSTDBY Run In Standby

The bit controls how the voltage reference behaves during the standby sleep mode.

ValueDescription
0 The voltage reference is halted during standby sleep mode.
1 The voltage reference is not stopped in standby sleep mode. If VREF.ONDEMAND = 1, the voltage reference will be running when a peripheral is requesting it. If VREF.ONDEMAND = 0, the voltage reference will always be running in standby sleep mode.

Bit 2 – VREFOE Voltage Reference Output Enable

ValueDescription
0 The Voltage Reference output is not available as an ADC input channel.
1 The Voltage Reference output is routed to an ADC input channel.

Bit 1 – TSEN Temperature Sensor Enable

ValueDescription
0 Temperature Sensor is disabled.
1 Temperature Sensor is enabled and routed to an ADC input channel.