US 9,812,887 B2
Secondary-battery monitoring device and battery pack
Shogo Nagata, Tokyo (JP); Yasuaki So, Kodaira (JP); Takeshi Yamaguchi, Fuchu (JP); and Norihito Kawaguchi, Akishima (JP)
Assigned to MITSUMI ELECTRIC CO., LTD., Tokyo (JP)
Filed by Mitsumi Electric Co., Ltd., Tokyo (JP)
Filed on Feb. 12, 2016, as Appl. No. 15/42,978.
Application 15/042,978 is a continuation of application No. 13/757,757, filed on Feb. 2, 2013, granted, now 9,312,723.
Claims priority of application No. 2012-046043 (JP), filed on Mar. 2, 2012.
Prior Publication US 2016/0164311 A1, Jun. 9, 2016
Int. Cl. H02J 7/00 (2006.01); G01R 19/165 (2006.01); H01M 10/42 (2006.01)
CPC H02J 7/007 (2013.01) [H02J 7/0029 (2013.01); H02J 7/0072 (2013.01); G01R 19/16542 (2013.01); H01M 10/4257 (2013.01); H02J 7/0004 (2013.01); H02J 7/0011 (2013.01); H02J 2007/0039 (2013.01); Y02E 60/12 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A secondary-battery monitoring device comprising:
first and second battery connection terminals to which a secondary battery is to be connected;
first and second external terminals to which a load or a charger is to be connected;
a first current path arranged between the first battery connection terminal and the first external terminal;
a second current path arranged between the second battery connection terminal and the second external terminal;
a switch circuit including a pair of FETs that control a flow of a charge current and a flow of a discharge current, respectively, the switch circuit being inserted in the second current path so as to control the charge current and the discharge current flowing in the secondary battery; and
a switch control unit,
wherein the switch control unit is provided with:
a second power-supply terminal connected to the second current path connecting the second battery connection terminal with a terminal of the switch circuit;
a first power-supply terminal to which a first power supply voltage from the secondary battery is supplied via the first current path with using the second power-supply terminal as a reference;
a pair of control terminals;
a driver circuit configured to supply a control voltage increasing along with an increase in the first power supply voltage, to a gate of the corresponding FET via the control terminal;
a detection terminal connected to the second current path connecting another terminal of the switch circuit with the second external terminal;
a detection circuit configured to monitor the charge current or the discharge current flowing in the second current path based on a detection voltage detected at the detection terminal, and to output a detection signal when the detection voltage reaches a predetermined value; and
a control circuit configured to supply the control voltage via the corresponding driver circuit in response to the detection signal, and to carry out control of shutting off the corresponding FET,
wherein an on resistance of the FET decreases along with an increase in the first power supply voltage,
wherein the detection circuit is provided with:
a comparator circuit configured to determine, based on a voltage of one input node serving as a reference voltage, magnitude of a voltage of another input node, and to output the detection signal based on a result of the determination; and
a voltage correction circuit configured to include
a unit to generate a correction voltage having a characteristic that varies along with an increase in the first power supply voltage, and
a unit to generate a correction detection voltage by adding the correction voltage to the detection voltage with such a polarity as canceling the slope of variation caused in the detection voltage, or a unit to generate a correction reference voltage by adding the correction voltage to a reference power supply voltage with such a polarity as canceling the slope of variation caused in the detection voltage,
wherein the comparator circuit has the one input node applied with the reference power supply voltage, and the other input node applied with the correction detection voltage, or has the one input node applied with the correction reference voltage, and the other input node applied with the detection voltage.