System and Reset Characteristics

Table 1. Reset, Brown-out and Internal Voltage Reference Characteristics
Symbol Parameter Condition Min Typ Max Units
VPOT Power-on Reset Threshold Voltage (rising)(1)     1.4 2.3 V
Power-on Reset Threshold Voltage (falling)     1.3 2.3 V
VRST RESET Pin Threshold Voltage   0.2   0.9 VCC
tRST Minimum pulse width on RESET Pin       1.5 μs
VBOT Brown-out Reset Threshold Voltage(2) BODLEVEL = 1 2.40 2.60 2.90 V
BODLEVEL = 0 3.70 4.00 4.50
tBOD Minimum low voltage period for Brown-out Detection BODLEVEL = 1   2   μs
BODLEVEL = 0   2   μs
VHYST Brown-out Detector hysteresis     130   mV
VBG Bandgap reference voltage   1.15 1.23 1.35 V
tBG Bandgap reference start-up time     40 70 μs
IBG Bandgap reference current consumption     10   μs
  1. 1.The Power-on Reset will not work unless the supply voltage has been below VPOT (falling).
  2. 2.VBOT may be below nominal minimum operating voltage for some devices. For devices where this is the case, the device is tested down to VCC = VBOT during the production test. This guarantees that a Brown-out Reset will occur before VCC drops to a voltage where correct operation of the microcontroller is no longer guaranteed. The test is performed using BODLEVEL = 1 and BODLEVEL = 0 for ATmega8A.