Atmel Xplained Evaluation Board AT32UC3A3-XPLD AT32UC3A3-XPLD データシート

32072H–AVR32–10/2012

The Brown-Out Detector 3V3 (BOD33) monitors one VDDIO supply pin and compares the sup-
ply voltage to the brown-out detection 3V3 level, which is typically calibrated at 2V7. The BOD33
is enabled by default, but can be disabled by software. The Brown-Out Detector 3V3 can either
generate an interrupt or a reset when the supply voltage is below the brown-out detection3V3
level. In any case, the BOD33 output is available in bit POSCSR.BOD33DET bit.

Note that any change to the BOD33.LEVEL field of the BOD33 register should be done with the
BOD33 deactivated to avoid spurious reset or interrupt.

The BOD33.LEVEL default value is calibrated to 2V7

See Electrical Characteristics chapter for parametric details.

VDDIO pin monitored by BOD33

The external reset detector monitors the state of the RESET_N pin. By default, a low level on
this pin will generate a reset. 

The Power Manager controls the calibration of the RC oscillator, voltage regulator, bandgap
voltage reference through several calibrations registers.

Those calibration registers are loaded after a Power On Reset with default values stored in fac-
tory-programmed flash fuses. 

Although it is not recommended to override default factory settings, it is still possible to override
these default values by writing to those registers. To prevent unexpected writes due to software
bugs, write access to these registers is protected by a “key”. First, a write to the register must be
made with the field “KEY” equal to 0x55 then a second write must be issued with the “KEY” field
equal to 0xAA.

H5

81

E5