The PAC194x and PAC195x products are one, two, three, and four-channel energy monitors, with Bus voltage monitors and current sense amplifiers, that feed high-resolution ADCs. There are two versions of the PAC194x and PAC195x: the PAC194x-1 and PAC195x-1 devices are for high-side current sensing and the PAC194x-2 and PAC195x-2 devices are for low-side current sensing. Digital circuitry performs power calculations and energy accumulation. This enables energy monitoring with integration periods up to one year or longer. Bus voltage, sense resistor voltage, and accumulated proportional power are stored in registers for retrieval by the system host or embedded controller. The sampling rate and energy integration period can be controlled over SMBus or I²C. Active channel selection, one-shot measurements and other controls are also configurable by SMBus or I²C. The PAC194x and PAC195x device family uses real-time calibration to minimize the offset error, and no input filters are required for these devices.