Negative voltage circuit based on dual charge pump
A negative voltage circuit includes a dual charging circuit, a pumping capacitor circuit, a dual discharging circuit, an output switch circuit, and a load capacitor circuit. The dual charging circuit is configured to operate in a start-up or normal operating mode during a charging mode, and supply a first current in the start-up mode higher than a second current in the normal operating mode. The pumping capacitor circuit is configured to charge based on a charging current from the dual charging circuit. The dual discharging circuit is configured to operate in the start-up mode or the normal operating mode during a discharging mode, and discharge the pumping capacitor to allow a third current in the start-up mode to flow between the pumping capacitor and the terminal of the second operating voltage. The third current in the start-up mode is higher than a fourth current in the normal operating mode.
1. A negative voltage circuit, comprising:
a dual charging circuit, connected between a terminal of a first power supply voltage and a middle node, configured to
operate in a start-up mode or a normal operating mode during a charging mode, and
supply a first current in the start-up mode higher than a second current in the normal operating mode;
a pumping capacitor circuit, connected between the middle node and a first capacitor node, configured to charge based on a charging current from the dual charging circuit;
a dual discharging circuit, connected between the middle node and a terminal of a second operating mode, configured to
operate in the start-up mode or the normal operating mode during a discharging mode, and
discharge the pumping capacitor to allow a third current in the start-up mode to flow between the pumping capacitor and the terminal of the second operating voltage, wherein the third current in the start-up mode is higher than a fourth current in the normal operating mode;
an output switch circuit connecting the first capacitor node to one of a terminal of the second operating voltage and an output terminal of a negative voltage circuit; and
a load capacitor circuit connected between the output terminal and a ground to stabilize a negative voltage at the output terminal.
2. The negative voltage circuit of claim 1 , wherein the dual charging circuit comprises:
a first charging switch, connected between the terminal of the first power supply voltage and the middle node, configured to be in an ON state in a charging operation during the start-up mode to supply the first current; and
a second charging switch, connected to the first charging switch in parallel, configured to be in an ON state in a charging operation during the normal operating mode to supply the second current less than the first current.
3. The negative voltage circuit of claim 2 , wherein the pumping capacitor circuit comprises a capacitor connected between the middle node and the first capacitor node.
4. The negative voltage circuit of claim 3 , wherein the dual discharging circuit comprises a first discharging switch, connected between the middle node and a terminal of a second power supply voltage, configured to be in an ON state in a discharging operation during the normal operating mode to supply the fourth current less than the third current.
5. The negative voltage circuit of claim 4 , wherein the output switch circuit comprises:
a ground switch, connected to the first capacitor node and the terminal of the second operating voltage, and configured to be in an ON state during the charging operation; and
an output switch, connected between the first capacitor node and the output terminal, and configured to be in ON state during the discharging operation.
6. The negative voltage circuit of claim 5 , wherein the load capacitor circuit is connected between the output terminal and a ground to stabilize the negative voltage at the output terminal.
7. A negative voltage circuit, comprising:
a dual charging circuit, connected between a terminal of a first power supply voltage and a middle node, configured to
operate in a start-up mode or a normal operating mode during a charging mode, and
supply a first current in the start-up mode higher than a second current in the normal operating mode;
a pumping capacitor circuit, connected between the middle node and a first capacitor node, configured to charge based on a charging current from the dual charging circuit;
a dual discharging circuit, connected between the middle node and a terminal of a second operating mode, configured to
operate in the start-up mode or the normal operating mode during a discharging mode, and
discharge the pumping capacitor to allow a third current in the start-up mode to flow between the pumping capacitor and the terminal of the second operating voltage, wherein the third current in the start-up mode is higher than a fourth current in the normal operating mode;
an output switch circuit connecting the first capacitor node to one of a terminal of the second operating voltage and an output terminal of a negative voltage circuit;
a load capacitor circuit connected between the output terminal and a ground to stabilize a negative voltage at the output terminal; and
a control circuit configured to control the start-up mode upon an operation being started, the normal operating mode subsequent to the start-up mode, and the charging mode and the discharging mode in the start-up mode and the normal operating mode, respectively.
8. The negative voltage circuit of claim 7 , wherein the control circuit comprises:
a PWM generation circuit configured to generate a PWM signal;
a mode select circuit configured to control the start-up mode based on the negative voltage upon the operation being started and generate the operating mode control signal for controlling the normal operation mode subsequent to the start-up mode;
a first driving signal generation circuit configured to generate first and second driving signals for controlling a charging of the dual charging circuit and a discharging of the dual discharging circuit based on the PWM signal and the operating mode control signal during the start-up mode; and
a second driving signal generation circuit configured to generate third and fourth driving signals for controlling a charging of the dual charging circuit and a discharging of the dual discharging circuit based on the PWM signal and the operation mode control signal during the normal operating mode.
9. The negative voltage circuit of claim 8 , wherein the mode select circuit comprises:
a comparison circuit configured to
transition from a low level to a high level upon the negative voltage being higher than or equal to a first reference voltage, and
transition from a high level to a low level upon the negative voltage being less than or equal to the second reference voltage.
10. The negative voltage circuit of claim 9 , wherein the dual charging circuit comprises:
a first charging switch, connected between the terminal of the first power supply voltage and the middle node, configured to be in an ON state in a charging operation during the start-up mode to supply the first current; and
a second charging switch, connected to the first charging switch in parallel, configured to be in an ON state in a charging operation during the normal operating mode to supply a second current less than the second current.
11. The negative voltage circuit of claim 10 , wherein the pump capacitor circuit comprises a capacitor connected between the middle node and the first capacitor node.
12. The negative voltage circuit of claim 11 , wherein the dual discharging circuit comprises:
a first discharging switch, connected between the middle node and a terminal of a second power supply voltage, configured to be in an ON state in a discharging operation during the start-up mode to supply the third current; and
a second discharging circuit, connected to the first discharging switch in parallel, configured to be in an ON state in a discharging operation during the normal operating mode to supply the fourth current less than the third current.
13. The negative voltage circuit of claim 12 , wherein the first driving signal generation circuit controls operations of the first charging switch and the first discharging switch using the first and second driving signals, respectively.
14. The negative voltage circuit of claim 13 , wherein the second driving signal generation circuit controls operations of the second charging switch and the second discharging switch using the third and fourth driving signals, respectively.
15. The negative voltage circuit of claim 13 , wherein the output switch circuit comprises:
a ground switch, connected between the first capacitor node and the terminal of the second operating voltage, configured to be in an ON state during the charging operation; and
an output switch, connected between the first capacitor node and the output terminal, configured to be in an ON state during the discharging operation.
16. The negative voltage circuit of claim 15 , wherein the load capacitor circuit comprises a load capacitor connected between the output terminal and a ground to stabilize the negative voltage at the output terminal.