Bandgap Reference - NXP Semiconductors MC9S08SU16 Reference Manual

Bandgap reference

6.3 Bandgap reference
This device includes an on-chip bandgap reference (≈1.2 V) connected to ADC channels.
The bandgap reference voltage does not drop under the full operating voltage even when
the operating voltage is falling. This reference voltage acts as an ideal reference voltage
for accurate measurements.
This device also includes a high accuracy voltage reference VREFH (~4.2 V). This
reference provides high accuracy reference to ADC and 6-bit DAC inside CMP.
MC9S08SU16 Reference Manual, Rev. 5, 4/2017
74 NXP Semiconductors