Patent ID: 8902011
Filing Date: 2014-12-02
Classification: H03B,H03L

Abstract:
1. A signal generating circuit for a real time clock device, comprising: an oscillating circuit for generating an oscillating signal; a voltage detecting circuit, for detecting a voltage level coupled with the signal generating circuit; a control circuit, coupled with the oscillating circuit and the voltage detecting circuit, for configuring the oscillating circuit to generate the oscillating signal with a first current in a first interval when the voltage level detected by the voltage level detecting circuit locates in a predetermined range, for configuring the oscillating circuit to generating the oscillating signal with a second current in a second interval, and for generating a clock signal according to the oscillating signal in a third interval; and a counter circuit, coupled with the oscillating circuit and the control circuit, for calculating a time value according to the oscillating signal, wherein when the voltage detecting circuit detects that the voltage level does not locate in the predetermined range after the third interval, the control circuit configures the oscillating circuit to generate the oscillating signal with the first current in a fourth interval, configures the oscillating circuit to generating the oscillating signal with the second current in a fifth interval, and generates the clock signal according to the oscillating signal in a sixth interval; the first interval is earlier than the second interval; the fourth interval is earlier than the fifth interval; the fifth interval is earlier than the sixth interval; the second interval is earlier than the third interval; and the second current is smaller than the first current, the control circuit calculating lapsed times of the first interval, the second interval, the third interval, the fourth interval, the fifth interval and the sixth interval according to the time value.