Composite integrated circuit for secondary battery, composite device for secondary battery, and battery pack

A composite integrated circuit includes a protection IC that controls a switching circuit inserted in a power supply line to allow or prevent discharging of the secondary battery, and a monitoring IC that includes a ground terminal connected to the power supply line at a position between the secondary battery and the switching circuit, measures a voltage of the secondary battery, and sends the measured voltage to an external apparatus. The protection IC outputs an activation signal to turn on the switching circuit to allow discharging of the secondary battery, and outputs a deactivation signal to turn off the switching circuit to prevent discharging of the secondary battery. The monitoring IC consumes less power while the deactivation signal is output by the protection IC than the monitoring IC consumes while the activation signal is output by the protection IC.