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53.3.2.4 SC[MODE_LV] = 11
Reserved
53.3.3 Internal voltage regulator
The VREF module contains an internal voltage regulator that can be enabled to provide
additional supply noise rejection. It is recommended that when possible, this regulator be
enabled to provide the optimum VREF performance.
If the internal voltage regulator is being used, the chop oscillator must also be enabled. A
specific sequence must be followed when enabling the internal regulator as follows:
1. Enable the chop oscillator (VREF_TRM[CHOPEN] = 1)
2. Configure the VREF_SC register to the desired settings with the internal regulator
disabled, VREF_SC[REGEN] = 0
3. Wait > 300ns
4. Enable the internal regulator by setting VREF_SC[REGEN] to 1
53.4 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.
Initialization/Application Information
K32 L2A Reference Manual, Rev. 2, 01/2020
1354
NXP Semiconductors
Summary of Contents for K32 L2A Series
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Page 122: ...Flash Memory Clock K32 L2A Reference Manual Rev 2 01 2020 122 NXP Semiconductors...
Page 158: ...Debug and security K32 L2A Reference Manual Rev 2 01 2020 158 NXP Semiconductors...
Page 174: ...Module Signal Description Tables K32 L2A Reference Manual Rev 2 01 2020 174 NXP Semiconductors...
Page 246: ...Application information K32 L2A Reference Manual Rev 2 01 2020 246 NXP Semiconductors...
Page 374: ...CMP Trigger Mode K32 L2A Reference Manual Rev 2 01 2020 374 NXP Semiconductors...
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