Step-up circuit using two frequencies
First Claim
1. A step-up circuit comprising:
- a selection control circuit, receiving an external power supply voltage, for setting a control signal at a first state in response to the external power-supply voltage being lower than a predetermined voltage which is lower than the external power-supply voltage at a stable state;
a clock generating circuit for providing a first clock with a first frequency when said control signal is at said first state and for providing a second clock with a second frequency when said control signal is at a second state, said second frequency being lower than said first frequency; and
a charging pump circuit driven by a selected one of said first and second clocks.
4 Assignments
0 Petitions
Accused Products
Abstract
A step-up circuit includes a selection control circuit 50 for activating a start/stop signal STP by detecting an external power-supply voltage Vcc, which is stable at 3.3 V, to reach 2.0 V or more, a ring oscillator circuit 30 for generating and outputting a clock of a high frequency Fs when the start/stop signal STP is inactive, a ring oscillator circuit 10 for generating a clock of a low frequency fo, a selection circuit 40 for selecting the output of the oscillator 30 when the start/stop signal STP is inactive and for selecting the output of the oscillator 10 when the start/stop signal is active, and a charging pump circuit 20 driven by the clocks. High frequency Fs is initially used to quickly bring an output voltage up to a desired operating level and low frequency fo is used, in order to conserve power, to maintain the operating level once a predetermined level of the external power supply voltage Vcc has been reached in order to conserve power.
-
Citations
10 Claims
-
1. A step-up circuit comprising:
-
a selection control circuit, receiving an external power supply voltage, for setting a control signal at a first state in response to the external power-supply voltage being lower than a predetermined voltage which is lower than the external power-supply voltage at a stable state; a clock generating circuit for providing a first clock with a first frequency when said control signal is at said first state and for providing a second clock with a second frequency when said control signal is at a second state, said second frequency being lower than said first frequency; and a charging pump circuit driven by a selected one of said first and second clocks. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A semiconductor device comprising a step-up circuit formed on a semiconductor chip, wherein said step-up circuit comprises:
-
a selection control circuit, receiving an external power supply voltage, for setting a control signal at a first state in response to the external power-supply voltage being lower than a predetermined voltage which is lower than the external power-supply voltage at a stable state; a clock generating circuit for providing a first clock with a first frequency when said control signal is at said first state and for providing a second clock with a second frequency when said control signal is at a second state, said second frequency being lower than said first frequency; and a charging pump circuit driven by a selected one of said first and second clocks. - View Dependent Claims (8, 9)
-
-
10. A boost circuit, in a semiconductor integrated circuit receiving a first power supply voltage and a second power supply voltage, which is lower than the first power supply voltage, to operate, comprising:
-
a detection circuit connected with a first power supply line having the first power-supply voltage, for detecting when the first power supply voltage is higher than a reference voltage level which is between the first power supply voltage and the second power supply voltage, and for outputting a detection signal; a clock generating circuit for outputting a clock signal with a frequency, the frequency changing to be lower in response to the detection signal indicating that the first power-supply voltage is higher than the reference voltage; and a charge pump circuit connected with the first power supply line for outputting a boost voltage in response to the clock signal.
-
Specification