Power rail switching
Updated: September 4, 2013
A system that implements rail switching requires nothing from the device manufacturer beyond the mandatory requirements of the bus and protocol. The system builder can only implement the rail switching scheme by using ACPI to provide rail control.
|In a rail control implementation, you should be aware of the electrical limitations and constraints of the device. Some devices may require special pads on the I2C clock and data lines to prevent current leakage into the device, if the device is on an active bus while without power.|
Figure 1 HID I2C Peripheral with Rail Switching Design