IMAGE FORMING APPARATUS, SYSTEM-ON-CHIP (SOC) UNIT, AND DRIVING METHOD THEREOF

摘要

An image forming apparatus is connected to a host device including first and second power domains which are separately supplied with power and includes first and second memories to be disposed in the second power domain, a main controller disposed in the first power domain and to perform a control operation using the first memory in a normal mode, and a sub-controller disposed in the second power domain and perform a control operation using the second memory in a power-saving mode, where when the normal mode is changed to the power-saving mode a power supply to the first power domain is shut off, the first memory operates in a self-refresh mode, and the main controller copies central processing unit (CPU) context information into a context storage unit, and when the power-saving mode is changed to the normal mode, the main controller is booted using the CPU context information stored in the context storage unit.

主权项

1. A method of driving a system-on-chip (SoC) unit which is connected to a host device and includes first and second power domains which are separately supplied with power through different power supply lines, where the second power domain includes first and second memories, a sub-controller to perform a control operation using the second memory in a power-saving mode, and a context storage unit to store context information, and the first power domain comprises a main controller to shut off a power supply thereto when a normal mode is changed to the power-saving mode and perform a control operation using the first memory in the normal mode, the method comprising:
when the normal mode is changed to the power-saving mode, changing the first memory to a self-refresh mode and copying central processing unit (CPU) context information, which is lost when shutting off the power supply to the first power domain, into the context storage unit; and when the power-saving mode is changed to the normal mode, booting the main controller using the CPU context information stored in the context storage unit.