SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 275

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

17.4
17.4.1
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
Supply Controller Functional Description
Supply Controller Overview
The device can be divided into two power supply areas:
The Supply Controller (SUPC) controls the supply voltage of the core power supply. The SUPC
intervenes when the VDDUTMI power supply rises (when the system is starting) or when the
Backup Low Power Mode is entered.
The SUPC also integrates the Slow Clock generator which is based on a 32 kHz crystal oscilla-
tor and an embedded 32 kHz RC oscillator. The Slow Clock defaults to the RC oscillator, but the
software can enable the crystal oscillator and select it as the Slow Clock source.
The Supply Controller and the VDDUTMI power supply have a reset circuitry based on the
NRSTB pin and a zero-power power-on reset cell. The zero-power power-on reset allows the
SUPC to start properly as soon as the VDDUTMI voltage becomes valid. The NRSTB pin allows
to reset the system from outside.
At startup of the system, once the backup voltage VDDUTMI is valid and the reset pin NRSTB is
not driven low and the embedded 32 kHz RC oscillator is stabilized, the SUPC starts up the core
by sequentially enabling the internal Voltage Regulator, waiting that the core voltage VDDCORE
is valid, then releasing the reset signal of the core “vddcore_nreset” signal.
Once the system has started, the user can program a supply monitor and/or a brownout detec-
tor. If the supply monitor detects a voltage on VDDUTMI that is too low, the SUPC can assert the
reset signal of the core “vddcore_nreset” signal until VDDUTMI is valid. Likewise, if the brownout
detector detects a core voltage VDDCORE that is too low, the SUPC can assert the reset signal
“vddcore_nreset” until VDDCORE is valid.
When the Backup Low Power Mode is entered, the SUPC sequentially asserts the reset signal
of the core power supply “vddcore_nreset” and disables the voltage regulator, in order to supply
only the VDDUTMI power supply. In this mode the current consumption is reduced to a few
microamps for Backup part retention. Exit from this mode is possible on multiple wake-up
sources including an event on FWUP pin or WKUP pins, or a Clock alarm. To exit this mode, the
SUPC operates in the same way as system startup.
• The Backup VDDBU Power Supply: including the Supply Controller, a part of the Reset
• The Core Power Supply: including the other part of the Reset Controller, the Brownout
Controller, the Slow Clock switch, the General Purpose Backup Registers, the Supply
Monitor and the Clock which includes the Real Time Timer and the Real Time Clock
Detector, the Processor, the SRAM memory, the FLASH memory and the Peripherals
SAM3X/A
SAM3X/A
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