Voltage measuring circuit and method

Abstract

A detection resistor is connected in parallel to two terminals that are to be measured. The values of currents following through the detection resistor are measured, and the measured current values are time-integrated. Further, the current value as integrated is divided by the integration time, thereby determining an average current value that is an average of the current values. The average current value is then converted to a digital signal, which is then transmitted to a calculation means (processor). The calculation means calculates, from the average current value and the resistance value of the detection resistor, a voltage value across the two terminals.

Description

technical field [0001] The present invention relates to a voltage measurement circuit and method suitable for measuring voltage between desired terminals. Background technique [0002] Typically, a secondary battery in which the amount of energy (electric power) charged and discharged is large is used while maintaining safety by, for example, a protection circuit. In particular, a lithium ion secondary battery has a higher energy density than other secondary batteries of the same battery capacity, and thus must be used with a protection circuit. [0003] The main functions of the protection circuit are overcharge protection and overdischarge protection. Overcharge and overdischarge are generally detected by monitoring the voltage across the terminals (positive and negative terminals) of the secondary battery. As a result, it is necessary to accurately measure the voltage across the terminals of the secondary battery to prevent overcharging and overdischarging. [0004] In...

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Problems solved by technology

As a result, the measurement accuracy of the inter-terminal voltage of the secondary battery decreases due to such noise

There is an additional concern that noise generated by drive equipment or stationary equipment may cause malfunction of a processor (such as a CPU) included in the protection circuit

[0010] exist figure 1 In the voltage measurement circuit of the background art shown in , the negative potential of the secondary battery that supplies electric power to a driving device or a fixed device (not shown) as a source of noise generation shares a ground potential with the processor, whereby there is such a concern that : Accurate measurement of the voltage between terminals of a secondary battery is hindered because noise is superimposed on the voltage divided by using a plurality of resistors

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