Datasheet

261
11011B–ATARM–21-Feb-12
SAM3N
261
11011B–ATARM–21-Feb-12
SAM3N
16.4.5 Power Supply Reset
16.4.5.1 Raising the Power Supply
As soon as the voltage VDDIO rises, the RC oscillator is powered up and the zero-power
power-on reset cell maintains its output low as long as VDDIO has not reached its target voltage.
During this time, the Supply Controller is entirely reset. When the VDDIO voltage becomes valid
and zero-power power-on reset signal is released, a counter is started for 5 slow clock cycles.
This is the time it takes for the 32 kHz RC oscillator to stabilize.
After this time, the voltage regulator is enabled. The core power supply rises and the brownout
detector provides the bodcore_in signal as soon as the core voltage VDDCORE is valid. This
results in releasing the vddcore_nreset signal to the Reset Controller after the bodcore_in signal
has been confirmed as being valid for at least one slow clock cycle.
Figure 16-3. Raising the VDDIO Power Supply
Zero-Power Power-On
Reset Cell output
22 - 42 kHz RC
Oscillator output
Fast RC
Oscillator output
Backup Power Supply
vr_on
bodcore_in
vddcore_nreset
NRST
proc_nreset
Note: After “proc_nreset” rising, the core starts fecthing instructions from Flash at 4 MHz.
periph_nreset
7 x Slow Clock Cycles
3 x Slow Clock
Cycles
3 x Slow Clock
Cycles
6.5 x Slow Clock
Cycles
TON Voltage
Regulator
Zero-Power POR
Core Power Supply