22.8.7 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   VREFOE   
Access R/WR/WR/W 
Reset 000 

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

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

ValueDescription
0x0 1.024V voltage reference typical value
0x2 2.048V voltage reference typical value
0x3 4.096V voltage reference typical value
Others Reserved

Bit 7 – ONDEMAND On Demand Control

The On Demand operation mode allows to enable or disable the voltage reference depending on 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 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.