The user should note that this part is tested and guaranteed to operate down to 4.5V (10%) and that VRST (min) is specified below that point. This indicates that there is a range of voltages [VMIN to V RST(min)] where the processor's operation is not guaranteed, but the reset trip point has not been reached. This should not be an issue in most applications, but should be considered when proper operation must be maintained at all times. For these applications, it may be desirable to use a more accurate external reset.