Charge pump to supply voltage bands
View Patent ↗The present invention provides a voltage generating circuit and a control method thereof which is capable of preventing an increase in the occupied area and suitable for raising the voltage of the power supply in a wide range. This voltage generating circuit comprises a first charge pump unit to which a first clock signal is inputted, wherein the first charge pump unit generates a voltage by pumping a voltage of a first external power supply in stages by a first voltage, a voltage selector that selects the voltage generated by the first charge pump unit or a voltage of a second external power supply in accordance with a voltage selection command signal, a level converter that converts a voltage level of the first clock signal into a second voltage level, and a second charge pump unit to which the second clock signal that has been converted by the level converter is inputted, wherein the second charge pump unit and that generates a voltage and by pumping the selected voltage or the voltage of the second external power supply.
1. A voltage generating circuit in which a plurality of charge pumps are arranged between an input and an output, comprising:
a first charge pump unit to which a first clock signal having a first voltage level is inputted, the first charge pump unit generating a first precharge pumping voltage by pumping a voltage of a first external power supply in stages by a first voltage;
a voltage selector that is coupled to any one of the first power supply and a second external power supply having a higher voltage value than the first external power supply, the voltage selector selecting from the first precharge pumping voltage generated by the first charge pump unit or the voltage of the second external power supply, in accordance with a voltage selection command signal;
a level converter that converts a voltage level of the first clock signal into a second voltage level that is higher than the first voltage level; and
a second charge pump unit to which a second clock signal having the second voltage level is inputted, the second charge pump unit generating a second precharge pumping voltage by pumping the first precharge pumping voltage or the voltage of the second external power supply selected by the voltage selector in stages by a second voltage with a greater potential difference than the first voltage.
2. The voltage generating circuit according to claim 1 , further comprising a voltage generation adjusting unit by which the first charge pump unit generates the first precharge pumping voltage after the first precharge pumping voltage is selected by the voltage selector.
3. The voltage generating circuit according to claim 2 , wherein the voltage generation adjusting unit includes a delay unit that delays a phase of at least one signal from the voltage selection command signal and an activation control signal of the first charge pump unit so as to generate a delay signal, and a generation unit that, in accordance with the delay signal or the at least one signal generates a voltage generation command signal for generating the first precharge pumping voltage.
4. The voltage generating circuit according to claim 1 , further comprising an assist circuit that assists a voltage value to be applied to the second charge pump unit so as to approximate the voltage value of the first external power supply or to the voltage value of the second external power supply.
5. The voltage generating circuit according to claim 4 , wherein the assist circuit includes an assist diode that is connected between a power line of the first external power supply and the second charge pump unit, or between a power line of the second external power supply and the second charge pump unit.
6. The voltage generating circuit according to claim 3 , the voltage generating circuit further comprising:
an output voltage adjusting unit that, when the first precharge pumping voltage has been selected by the voltage selection unit, lowers an output voltage value of the second charge pump unit after the second charge pump unit is stopped; and
a command signal output unit that, after the output voltage
a command signal output unit that, after the output voltage value is lowered than a reference voltage value, outputs a connection command signal that instructs the voltage selection unit to connect with the first external power supply.
7. The voltage generating circuit according to claim 1 further comprising a clock signal delay unit that delays a phase of the first clock signal to be inputted to the first charge pump than a phase of the second clock signal to be inputted to the second charge pump unit.
8. The voltage generating circuit according to claim 1 , wherein plurality of charge pump units of at least one of the first charge pump unit and the second charge pump unit are connected in parallel to each other, the voltage generating circuit further comprising a phase adjusting unit that brings the phases of clock signals of at least one of the first clock signal to be inputted to the first charge pump unit and the second clock signal to be inputted to the second charge pump unit to be different from each other.
9. The voltage generating circuit according to claim 8 , wherein plurality of the second charge pump units are connected in parallel to each other, comprising:
a detector that detects that a voltage value changing in accordance with an output voltage value of the second charge pump unit has become higher than a predetermined voltage value;
a clock signal supply stopping unit that, in accordance with a detection result of the detector, stops input of the second clock signal to at least one second charge pump unit of the plurality of second charge pump units.
10. A control method of a voltage generating circuit including a plurality of pumping steps for generating a precharge pumping voltage between an input and an output, comprising:
a first pumping step that uses a first clock signal having a first voltage level so as to generate a first precharge pumping voltage, by pumping a voltage of a first external power supply in stages by a first voltage;
a voltage selecting step that uses the first external power supply or a second external power supply having a higher voltage value than the first external power supply so as to select from the first precharge pumping voltage generated by the first pumping step and a voltage of the second external power supply, in accordance with a voltage selection command signal;
a level converting step that converts a voltage level of the first clock signal to a second voltage level that is higher than the first voltage level, and
a second pumping step that uses the second clock signal having the second voltage level converted by the level converting step so as to generate a second precharge pumping voltage by pumping the first precharge pumping voltage or the voltage of the second external power supply selected by the voltage selecting step in stages by a second pumping step with a greater potential difference than the first voltage.
11. The control method according to claim 10 , further comprising a voltage generation adjusting step by which the first pumping step generates the first precharge pumping voltage after the first precharge pumping voltage is selected by the voltage selecting step.
12. The control method according to claim 11 , wherein the voltage generation adjusting step comprises:
a delay step that delays a phase of at least one signal of the voltage selection command signal and an activation control signal of the first charge pump unit so as to generate a delay signal, and
a generation step that, in accordance with the delay signal or the at least one signal, generates a voltage generation command signal for generating the first precharge pumping voltage.
13. The control method according to claim 10 , the method further comprising the step of:
assisting a voltage value to be used in the second pumping step so as to approximate the voltage value of the first external power supply or to the voltage value of the second external power supply.
14. The control method according to claim 12 , the control method further comprising the steps of:
output voltage adjusting step that, when the first precharge pumping voltage has been selected by the voltage selecting step, lowers an output voltage value generated by the second pumping step after the second pumping step is stopped, and
instruction step that, after the output voltage value generated by the second pumping step is lowered than a reference voltage value, instructs the voltage selecting step to use the first external power supply in the voltage selecting step.
15. The control method according to claim 10 , the control method further comprising a clock signal delay step that delays a phase of the first clock signal to be used in the first pumping step than a phase of the second clock signal to be used in the second pumping step.
16. The control method according to claim 10 , wherein a plurality of pumping steps of at least one of the first pumping step and the second pumping step are executed in parallel, the control method further comprising a phase adjusting step that brings the phases of clock signals of at least one of the first clock signal to be used in the first pumping step and the second clock signal to be used in the second pumping step to be different from each other.
17. The control method according to claim 16 , wherein a plurality of the second pumping steps are executed in parallel, comprising:
a detecting step that detects that a voltage value changing in accordance with an output voltage value of the second pumping step has become higher than a predetermined voltage value; and
a clock signal supply stopping step that, in accordance with a detection result of the detecting step, stops use of the second clock signal in at least one second pumping step of the plurality of second pumping steps.
18. A nonvolatile storage device, comprising a voltage generating circuit in which a plurality of charge pumps are arranged between an input and an output, comprising: a first charge pump unit to which a first clock signal having a first voltage level is inputted, the first charge pump unit generating a first precharge pumping voltage by pumping a voltage of a first external power supply in stages by a first voltage; a voltage selector that is connected to any one of the first power supply and a second external power supply having a higher voltage value than the first external power supply, the voltage selector selecting from the first precharge pumping voltage generated by the first charge pump unit or the voltage of the second external power supply, in accordance with a voltage selection command signal; a level converter that converts a voltage level of the first clock signal into a second voltage level that is higher than the first voltage level; and a second charge pump unit to which a second clock signal having the second voltage level is inputted, the second charge pump unit generating a second precharge pumping voltage by pumping the first precharge pumping voltage or the voltage of the second external power supply selected by the voltage selector in stages by a second voltage with a greater potential difference than the first voltage,
wherein, a first control signal that maintains activity of the first charge pump unit is inputted to the first charge pump unit, and
a second control signal that is different control signal from the first control signal and maintains activity of the second charge pump is inputted to the second charge pump unit.
19. The nonvolatile storage device according to claim 18 , comprising:
a program mode that executes writing into a nonvolatile memory element, and
an erase mode that executes erasing from the nonvolatile memory element,
wherein the second charge pump includes a third charge pump unit that generates a first voltage in accordance with the program mode, and a fourth charge pump unit that generates a second voltage in accordance with the erase mode.