Technology for reducing controller standby power consumption

Amid increasing environmental awareness, it is necessary to reduce the power consumption and CO₂ emissions of multifunction devices in offices. They are equipped with a sleep mode to be used when they are idle to reduce power consumption.

Massively reduce power consumption in sleep mode

The controller is a unit that controls the entire multifunction device. Even when the device is in the sleep mode, it needs to swiftly respond to processing requests from the network, such as printing instructions from a host computer, job monitoring and status checks. It is impossible to completely power off all of its components. In the circuit that constitutes part of the controller, the central processing unit (CPU) inside the system-on-a-chip (SoC)^*1consumes a significant amount of electricity.

At FUJIFILM Business Innovation, we use the configuration in Figure 1 for the controllers of multifunction devices. They have two functions. One is quickly waking up the CPU and the other is to make memory available to store communication packets. In sleep mode, the CPU is powered off and the memory is shifted to low-power mode and it maintains different settings. In this mode, the SoC keeps the power management circuit and other minimum circuits necessary for waking up active. When a network processing request from a host computer is received, it powers up the CPU and returns the saved settings to it. This enables the CPU to wake swiftly. This design configuration enables the device to return the necessary responses while storing communication packets in memory. Ensuring optimal power control, it complies with power-efficient network standards and enhances network performance.

Figure 1: Configuration of the controller

This technology for reducing the power consumption of the controller achieves the industry's lowest sleep power consumption of 0.5 WAC (in CPFS configuration).

• *1 A system-on-a-chip (SoC) integrates a series of necessary functions, or a system, on a single semiconductor chip.