Power on reset generating circuit and method thereof
AssigneeHoltek Semiconductor Inc.
InventorYU-REN CHEN
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Abstract
The invention mainly relates to a power on reset signal generating circuit and method thereof wherein said reset signal remains as a constant being independent of rising or descending power or repeated switching. The power on reset signal circuit can be implemented by a conventional RC power on reset circuit together with a coupled N-type transistor switch to charge or discharge the capacitor inside the conventional RC power on reset circuit.
Claims23
A power on reset generating method, comprising:
- (a) arising the power supply;
- (b) establishing a reference voltage according to said arising power supply;
- (c) judging whether said reference voltage is lower than a transient point of an inverter, if no, goes to step (b), if yes, goes to step (d);
- (d) charging a capacitor inside a conventional RC power on reset generating circuit;
- and
- (e) generating a reset signal to a system during the capacitor charging process.
A circuit controlling the discharging of a capacitor inside a conventional RC power on reset generating circuit, comprising:
- a voltage generator;
- a first inverter, coupled to said generator's output;
- a second inverter, coupled to said first inverter's output;
- and
- a N-typed transistor switch, wherein its gate is coupled to said second inverter's output.
A power on reset generating circuit, comprising:
- a capacitor, wherein one side of said capacitor is coupled to ground;
- a resistor, wherein one side of said resistor is coupled to a power supply, and another side of said resistor is coupled to another side of said capacitor;
- a buffer, wherein its output is coupled to another side of said capacitor;
- a voltage detecting circuit, said detecting circuit outputs a signal for charging and discharging;
- and
- a N-typed transistor switch, wherein a drain of said switch is coupled to another side of said capacitor and a gate of said switch is coupled to said signal for charging and discharging.
Dependencies are inferred from the claim text.