SYSCFG configuration register 3
| EN_BGAP | Vref Enable bit |
| SEL_VREF_OUT | BGAP_ADC connection bit |
| ENBUF_BGAP_ADC | VREFINT reference for ADC enable bit |
| ENBUF_SENSOR_ADC | Sensor reference for ADC enable bit |
| ENBUF_VREFINT_COMP | VREFINT reference for comparator 2 enable bit |
| ENREF_RC48MHz | VREFINT reference for 48 MHz RC oscillator enable bit |
| REF_RC48MHz_RDYF | VREFINT for 48 MHz RC oscillator ready flag |
| SENSOR_ADC_RDYF | Sensor for ADC ready flag |
| VREFINT_ADC_RDYF | VREFINT for ADC ready flag |
| VREFINT_COMP_RDYF | VREFINT for comparator ready flag |
| VREFINT_RDYF | VREFINT ready flag |
| REF_LOCK | REF_CTRL lock bit |