
4. Enable the internal regulator by setting VREF_SC[REGEN] to 1
37.4 Initialization/Application Information
The Voltage Reference requires some time for startup and stabilization. After
SC[VREFEN] = 1, SC[VREFST] can be monitored to determine if the stabilization and
startup is completed when the chop oscillator is not enabled. When the chop oscillator is
enabled, the settling time of the internal bandgap reference is defined by Tchop_osc_stup
(chop oscillator start up time). You must wait this time (Tchop_osc_stup) after the
internal bandgap has been enabled to ensure the VREF internal reference voltage has
stabilized.
When the Voltage Reference is already enabled and stabilized, changing SC[MODE_LV]
will not clear SC[VREFST] but there will be some startup time before the output voltage
at the VREF_OUT pin has settled. This is the buffer start up delay (Tstup) and the value
is specified in the appropriate device data sheet. Also, there will be some settling time
when a step change of the load current is applied to the VREF_OUT pin. When the 1.75V
VREF regulator is disabled, the VREF_OUT voltage will be more sensitive to supply
voltage variation. It is recommended to use this regulator to achieve optimum
VREF_OUT performance.
The TRM[CHOPEN], SC[REGEN] and SC[ICOMPEN] bits must be written to 1 to
achieve the performance stated in the device data sheet.
NOTE
See section "Internal voltage regulator" for details on the
required sequence to enable the internal regulator.
Chapter 37 Voltage Reference (VREFV1)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors
865
Содержание K22F series
Страница 2: ...K22F Sub Family Reference Manual Rev 4 08 2016 2 NXP Semiconductors...
Страница 150: ...Private Peripheral Bus PPB memory map K22F Sub Family Reference Manual Rev 4 08 2016 150 NXP Semiconductors...
Страница 168: ...Module clocks K22F Sub Family Reference Manual Rev 4 08 2016 168 NXP Semiconductors...
Страница 198: ...Security Interactions with other Modules K22F Sub Family Reference Manual Rev 4 08 2016 198 NXP Semiconductors...
Страница 258: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 258 NXP Semiconductors...
Страница 292: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 292 NXP Semiconductors...
Страница 398: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 398 NXP Semiconductors...
Страница 628: ...Initialization and application information K22F Sub Family Reference Manual Rev 4 08 2016 628 NXP Semiconductors...
Страница 740: ...Initialization Application Information K22F Sub Family Reference Manual Rev 4 08 2016 740 NXP Semiconductors...
Страница 750: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 750 NXP Semiconductors...
Страница 816: ...Application information K22F Sub Family Reference Manual Rev 4 08 2016 816 NXP Semiconductors...
Страница 866: ...Initialization Application Information K22F Sub Family Reference Manual Rev 4 08 2016 866 NXP Semiconductors...
Страница 890: ...Application information K22F Sub Family Reference Manual Rev 4 08 2016 890 NXP Semiconductors...
Страница 1028: ...Initialization Procedure K22F Sub Family Reference Manual Rev 4 08 2016 1028 NXP Semiconductors...
Страница 1040: ...Example configuration for chained timers K22F Sub Family Reference Manual Rev 4 08 2016 1040 NXP Semiconductors...
Страница 1118: ...Device mode IRC48 operation K22F Sub Family Reference Manual Rev 4 08 2016 1118 NXP Semiconductors...
Страница 1122: ...USB Voltage Regulator Module Signal Descriptions K22F Sub Family Reference Manual Rev 4 08 2016 1122 NXP Semiconductors...
Страница 1180: ...Initialization application information K22F Sub Family Reference Manual Rev 4 08 2016 1180 NXP Semiconductors...
Страница 1302: ...Application information K22F Sub Family Reference Manual Rev 4 08 2016 1302 NXP Semiconductors...
Страница 1374: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 1374 NXP Semiconductors...