Charge and discharge control circuit and battery device

Patent metadata

Field	Value
Publication number	US-9647465-B2
Application number	US-201514711343-A
Country	US
Kind code	B2
Filing date	May 13, 2015
Priority date	May 14, 2014
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

A short-circuit and overcurrent detecting circuit includes a reference voltage circuit including a constant current circuit, a first impedance element, a first transistor having a resistance value depending a voltage of a secondary battery, a second impedance element, and a second transistor having a resistance value depending the voltage of the secondary battery, which are connected in series. The reference voltage circuit outputs a first reference voltage from a node of the constant current circuit and the first impedance element, and outputs a second reference voltage from a node of the first transistor and the second impedance element. The short-circuit and overcurrent detecting circuit further includes: a first comparator circuit for comparing a voltage of an overcurrent detecting terminal with the first reference voltage; and a second comparator circuit for comparing the voltage of the overcurrent detecting terminal with the second reference voltage.

First claim

What is claimed is:

1. A charge and discharge control circuit, comprising:
a control circuit configured to detect a voltage and abnormality of a secondary battery; and
a short-circuit and overcurrent detecting circuit configured to detect an overcurrent and a short circuit based on a voltage of an overcurrent detecting terminal,
the short-circuit and overcurrent detecting circuit comprising:
a reference voltage circuit comprising a constant current circuit, a first impedance element connected to the constant current circuit, a first transistor including a drain connected to the first impedance element, and having a resistance value that is changed depending on the voltage of the secondary battery, a second impedance element connected to a source of the first transistor, and a second transistor including a drain connected to the second impedance element, and having a resistance value that is changed depending on the voltage of the secondary battery, the reference voltage circuit being configured to output a first reference voltage from a node of the constant current circuit and the first impedance element, and output a second reference voltage from a node of the first transistor and the second impedance element;
a first comparator circuit configured to compare the voltage of the overcurrent detecting terminal with the first reference voltage; and
a second comparator circuit configured to compare the voltage of the overcurrent detecting terminal with the second reference voltage.

2. A charge and discharge control circuit according to claim 1 ,
wherein the first impedance element comprises a third transistor having a resistance value that is changed depending on the voltage of the secondary battery, and
wherein the second impedance element comprises a fourth transistor having a resistance value that is changed depending on the voltage of the secondary battery.

3. A battery device, comprising:
a secondary battery;
a charge and discharge control switch connected in a charge and discharge path of the secondary battery; and
the charge and discharge control circuit according to claim 1 configured to monitor a voltage of the secondary battery to control the charge and discharge control switch.

4. A battery device according to claim 3 , further comprising a resistor connected in the charge and discharge path between the secondary battery and an external terminal, in which the charge and discharge control switch is connected.

Assignees

• Seiko Instr Inc
• Sii Semiconductor Corp

Inventors

• Ono Takashi
• Koike Toshiyuki
• Abe Satoshi
• Maetani Fumihiko

Classifications

• H02J7/933

  the cycle being controlled or terminated in response to electric parameters · CPC title

• H02J7/855

  with circuits adapted for supplying loads from the battery · CPC title

• H02J7/62

  against overcurrent · CPC title

• G01R31/50 Primary

  Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections (testing of sparking plugs H01T13/58) · CPC title

• G01R31/382

  Arrangements for monitoring battery or accumulator variables, e.g. SoC · CPC title