Charge/discharge control circuit and battery device

• US 9,214,821 B2
• Filed: 02/05/2014
• Issued: 12/15/2015
• Est. Priority Date: 02/06/2013
• Status: Expired due to Fees

• Current Assignee: Ablic Inc. (Minebea Mitsumi, Inc.)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Koike, Toshiyuki
• Primary Examiner(s): Lin, Sun
• Application Number:
  US14/173,496
• Publication Number:
  US 20140217988A1
• Time in Patent Office: 678 Days
• Field of Search: 320/134
• US Class Current: 1/1
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]

Abstract

The level shifter circuit includes: a first transistor including a gate connected to an input terminal of the level shifter circuit and a source connected to a first power supply terminal; a first resistor including one terminal connected to the input terminal of the level shifter circuit; a second transistor including a gate connected to another terminal of the first resistor, a drain connected to a drain of the first transistor, and a source connected to a terminal for inputting the voltage subjected to the level conversion; and a third transistor including a gate and a drain connected to the another terminal of the first resistor, and a source connected to the terminal for inputting the voltage subjected to the level conversion. Further, the battery device includes the charge/discharge control circuit.

Claims

1. A charge/discharge control circuit for controlling charge and discharge of a secondary battery to be connected between a first terminal and a second terminal,

wherein the charge/discharge control circuit comprises:

a control circuit, connected between the first terminal and the second terminal, for monitoring a voltage of the secondary battery;

a level shifter circuit for level-converting a voltage of a charge control signal output from the control circuit; and

a third terminal for inputting the voltage subjected to the level-converting, and

wherein the level shifter circuit comprises;

a first transistor of a first conductivity type, including a gate connected to an input terminal of the level shifter circuit and a source connected to the first terminal;

a first resistor including one terminal connected to the input terminal of the level shifter circuit;

a second transistor of a second conductivity type, including a gate connected to another terminal of the first resistor, a drain connected to a drain of the first transistor, and a source connected to the third terminal; and

a third transistor of the second conductivity type, including a gate and a drain connected to said another terminal of the first resistor, and a source connected to the third terminal.

2. A charge/discharge control circuit according to claim 1, wherein the level shifter circuit further comprises:

a Zener diode including an anode connected to the drain of the first transistor and a cathode connected to the first terminal; and

a second resistor connected between the drain of the first transistor and the drain of the second transistor.

3. A charge/discharge control circuit according to claim 1, wherein the level shifter circuit further comprises:

a diode including a cathode connected to the drain of the first transistor and an anode connected to the second terminal; and

a second resistor connected between the drain of the first transistor and the drain of the second transistor.

4. A battery device, comprising:

a chargeable/dischargeable secondary battery;

a charge/discharge control switch provided in a charge/discharge path of the chargeable/dischargeable secondary battery; and

the charge/discharge control circuit according to claim 1, for monitoring a voltage of the chargeable/dischargeable secondary battery and controlling charge and discharge of the chargeable/dischargeable secondary battery by turning on and off the charge/discharge control switch.