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PAC - Peripheral Access Controller
on page 50
23.5.9. Analog Connections
Not applicable.
23.6. Functional Description
23.6.1. Voltage Regulator System Operation
23.6.1.1. Enabling, Disabling, and Resetting
The LDO main voltage regulator is enabled after any Reset. The main voltage regulator (MAINVREG) can
be disabled by writing the Enable bit in the VREG register (VREG.ENABLE) to zero. The main voltage
regulator output supply level is automatically defined by the performance level or the sleep mode selected
in the Power Manager module.
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23.6.1.2. Initialization
After a Reset, the LDO voltage regulator supplying VDDCORE is enabled.
23.6.1.3. Selecting a Voltage Regulator
In active mode, the type of the main voltage regulator supplying VDDCORE can be switched on the fly.
The two alternatives are a LDO regulator and a Buck converter.
The main voltage regulator switching sequence:
•
The user changes the value of the Voltage Regulator Selection bit in the Voltage Regulator System
Control register (VREG.SEL)
•
The start of the switching sequence is indicated by clearing the Voltage Regulator Ready bit in the
STATUS register (STATUS.VREGRDY=0)
•
Once the switching sequence is completed, STATUS.VREGRDY will read '1'
The Voltage Regulator Ready (VREGRDY) interrupt can also be used to detect a zero-to-one transition of
the STATUS.VREGRDY bit.
23.6.1.4. Voltage Scaling Control
The VDDCORE supply will change under certain circumstances:
•
When a new performance level (PL) is set
•
When the standby sleep mode is entered or left
•
When a sleepwalking task is requested in standby sleep mode
To prevent high peak current on the main power supply and to have a smooth transition of VDDCORE,
both the voltage scaling step size and the voltage scaling frequency can be controlled: VDDCORE is
changed by the selected step size of the selected period until the target voltage is reached.
The Voltage Scaling Voltage Step field is in the VREG register, VREG.VSVSTEP. The Voltage Scaling
Period field is VREG.VSPER.
The following waveform shows an example of changing performance level from PL0 to PL2.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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