Voltage converting circuit

• US 20090167419A1
• Filed: 12/19/2008
• Published: 07/02/2009
• Est. Priority Date: 12/28/2007
• Status: Abandoned Application

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: NEC Electronics Corporation (Renesas Electronics Corporation)
• Inventors: Sakaguchi, Makoto
• Application Number:
  US12/314,980
• Publication Number:
  US 20090167419A1
• Time in Patent Office: Days
• US Class Current: 327/536
• CPC Class Codes: H02M 3/073 Charge pumps of the Schenkel-type
• CPC Class Codes: H02M 3/076 the clock signals being boosted to a value being higher than the input voltage value

Abstract

Leakage current flowing into load is prevented when a charge pump circuit operation is halted. The charge pump circuit converts supply voltage, supplied to a supply-voltage input terminal, to an output signal having desired voltage value and outputs the signal to an output terminal. A first bypass circuit, connected between the supply-voltage input terminal and a supply node of the charge pump circuit, forms a bypass between the supply-voltage input terminal and the supply node only when a voltage value at the supply node is low compared with a supply voltage value supplied to the supply-voltage input terminal. A second bypass circuit connected between the output terminal and the supply node, forms a bypass between the output terminal and the supply node only when the voltage value at the supply node is low compared with the voltage value at the output terminal.

Claims

1. A voltage converting circuit comprising:

a charge pump circuit that converts supply voltage supplied to a supply-voltage input terminal to an output signal of a desired voltage value and outputs the signal to an output terminal;

a first bypass circuit which is connected between the supply-voltage input terminal and a supply node of said charge pump circuit, and forms a bypass between the supply-voltage input terminal and the supply node only in a case where a voltage value at the supply node is closer to ground voltage in comparison with a supply voltage value supplied to the supply-voltage input terminal; and

a second bypass circuit which is connected between the output terminal and the supply node, and forms a bypass between the output terminal and the supply node only in a case where the voltage value at the supply node is closer to ground voltage in comparison with the voltage value at the output terminal.

2. The circuit according to claim 1, wherein the supply voltage is a positive voltage;

said first bypass circuit comprises a first diode having an anode terminal connected to the supply-voltage input terminal and a cathode terminal connected to the supply node; and

said second bypass circuit comprises a second diode having an anode terminal connected to the output terminal and a cathode terminal connected to the supply node.

3. The circuit according to claim 1, wherein the supply voltage is a negative voltage;

said first bypass circuit comprises a first diode having a cathode terminal connected to the supply-voltage input terminal and an anode terminal connected to the supply node; and

said second bypass circuit comprises a second diode having a cathode terminal connected to the output terminal and an anode terminal connected to the supply node.

4. The circuit according to claim 1, wherein said first bypass circuit comprises a MOSFET which is diode-connected, and said second bypass circuit comprises a MOSFET which is diode-connected.

5. The circuit according to claim 1, wherein said level shifter controls one or more transistors connected between said supply-voltage input terminal and said output terminal so as to make up a charge pump circuit.

6. The circuit according to claim 5, wherein said level shifter is formulated so as to provide at least two levels of output signals for controlling said transistor(s) in accordance to a supply voltage at the supply node.

7. A semiconductor integrated circuit comprising said voltage converting circuit according to claim 1.