Disable switching regulator during spin-up (or spin-up with sleep state)
Publication Date: 2014-Jun-24
The IP.com Prior Art Database
Disclosed is a system that enables spinning up of the HDD motor without intervention from SoC, resulting in reduction of spin-up time and reduction of peak power current. Spin up time reduction and of peak supply current mitigation are the trade off. By disabling switching regulator including all R/W channel and Interface, almost 100% supply current can be consumed for spindle motor.
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Spin-up process consists of (1) Rotor position sensing at the motor stopped condition,
(2)Spindle Back EMF detection, (3) Voltage apply onto motor phases based on the back EMF, which requires firmware control. Hence SoC must be kept active. That is to say SoC is not consuming power for itself.
Automatic spin-up implementation into combo driver is an idea however, there are still issues. Since total HDD supply current consumption is limited and almost 100% of the current is consumed by spindle during spin-up, it is not possible to utilize saved firmware resource for other purposes. Furthermore, Reset will be occurred if power regulator is turned off during spin-up, and after re-enable the regulator, the firmware goes back to the beginning, making spin-up start from the scratch.
Latest SoC has a power island concept. This is to save as much as power when the drive is in sleep mode, or EPO (Emergency Power Off) state. After putting the SoC into sleep mode, by turning off power monitor function Reset will not be occurred even if the switching regulator is turned off. By utilizing this function during spin-up it is possible to reduce spin-up peak current, or to reduce the spin-up time by keeping the same peak current. SoC can know that spin-up routine is ongoing since the register setting is kept before going into the sleep mode. Flow chart is shown below Figure.
Put SoC in sleep mode
Disable Combo Power Monitor
Disable Switching Regula...