NXP Semiconductors K32 L2A Series, Reference Manual, Page: 1349 / 1379

VREF_TRM field descriptions (continued)
Field Description
6
CHOPEN
Chop oscillator enable. When set, the internal chopping operation is enabled and the internal analog offset
will be minimized.
CHOPEN bit is set during factory trimming of the VREF voltage. CHOPEN bit should be written to 1 to
achieve the performance stated in the data sheet.
If the internal voltage regulator is being used (REGEN bit is set to 1), then the chop oscillator must also be
enabled.
If the chop oscillatorwill be used in very low power modes, then the system (bandgap) voltage reference
must also be enabled. See the chip-specific VREF information (also known as "chip configuration" details)
to see how this can be achieved.
0 Chop oscillator is disabled.
1 Chop oscillator is enabled.
TRIM Trim bits
These bits change the resulting VREF by approximately ± 0.5 mV for each step. The trim value is stored in
IFR and loaded out of reset.
When test_mux_en=1:
TRIM[2:0] test_mux_out_pos test_mux_out_neg
000 vbg test_res
001 vbg vssa
010 vbe vssa
011 p7_trim vssa
1xx v_1p75 vssa
NOTE: Min = minimum and max = maximum voltage reference output. For minimum and maximum
voltage reference output values, refer to the Data Sheet for this chip.
000000 Min
000001 Max–(31 mV)
.... ....
111111 Max
Chapter 53 Voltage Reference (VREF)
K32 L2A Reference Manual, Rev. 2, 01/2020
NXP Semiconductors 1349