7.21 Power-On Reset Characteristics
VDD_VCO, VDDO_12, VDDO_34, VDD_REF = 1.8 V ± 5%, 2.5 V ± 5%, 3.3 V ± 5% and TA = -40°C to 105°C
PARAMETER |
TEST CONDITIONS |
MIN |
TYP |
MAX |
UNIT |
VTHRESHOLD |
POR threshold voltage(1) |
|
0.875 |
|
1.275 |
V |
tSTARTUP |
Start-up time |
Start-up time after VDD reaches 95% to the time outputs are toggling with correct frequency (input = crystal or external clock) |
|
9 |
|
ms |
tVDD |
Power supply ramp time(2) |
timing requirement for any VDD pin while PDN=LOW |
0.1 |
|
30 |
ms |
(1) POR threshold voltage is the power supply voltage at which the internal reset is deasserted. It is qualified internally with PDN.
(2) VDD pin should monotonically reach 95% of its final value within supply ramp time. Parameters specified by characterization. All VDD pins were tied together for this evaluation. For non-monotonic or slower power supply ramp, it is recommended to pull-down PDN pin until VDD pins have reached 95% of its final value. PDN pin has a 50 kΩ pullup resistor. When PDN pin cannot be actively controlled, TI recommends to add a capacitor to GND on PDN pin to delay the release of reset.