PFP

Dual Secure Design for Power Failure Protection
SP Industrial Implements Dual Secure Design for Power Failure Protection (PFP)

SP Industrial's complete series of solid-state drives are equipped with a power shielding firmware architecture that protects them by sensing unstable voltage and powering down to stop receiving host commands.
SP Industrial's R series of SSDs uses Advanced PFP with industrial-grade polymer capacitors to allow more time for data to be flushed from temporary memory (DRAM cache) to permanent storage (FLASH) during unexpected power loss situations.

How Does the SSD Controller Manage Power Failure?

The SSD firmware is stored in a system block within the NAND flash memory. When the system powers on, the SSD loads the relevant mapping tables and initialization commands into the DRAM for the controller to use (Figure 1-A).

If the voltage drops below 4V (Figure 1-B), the SSD controller activates the power protection function. During this process, the controller begins flushing data from the DRAM cache into the flash memory to ensure user data is safely stored. Simultaneously, the controller stops accepting commands from the host to protect the SSD (Figure 1-C). At this stage, the host cannot detect the SSD, and it will remain inactive until the voltage stabilizes again.

If the voltage drops further to below 2.7V (Figure 1-D), the SSD controller issues a FLUSH command to write the mapping table back into the system block in the flash memory. During this time, the host will still be unable to detect or interact with the SSD, even if power is restored. To resume normal operation, the host must perform a power cycle to restart the SSD.

During SSD operation, data is temporarily stored in the DRAM cache to reduce performance differences between the host interface and the NAND flash memory. However, in cases of unexpected sudden power loss, such as unplugging the power from the system, sudden battery loss, or unplugging devices from the system, the flushing process may not complete, which could cause serious device failure. Silicon Power's Dual Secure Design for Power Failure Protection (PFP) prevents such issues with a firmware-based protection mechanism and a capacitor backup circuit.

How Does the Advanced PFP Mechanism Work?

The power shielding function integrates built-in voltage detection technology and firmware mechanisms. The trigger alert can monitor abnormal power drops and take immediate action, such as prohibiting data receipt from the host and backing up mapping and linking tables into flash memory, as soon as a potential power failure is detected. Advanced PFP is a method to gain more time for the data flushing process from DRAM cache to flash during sudden power outages by using dedicated polymer capacitor components. These capacitors charge during power on and provide power to the SSD circuits during sudden power outages. SP Industrial's Advanced PFP technology SSD provides at least 20 milliseconds to ensure the data flushing task can be completed within the discharge time. Furthermore, it always passes the power cycling test under abnormal conditions at least 3,000 times.

How Does the SSD Controller Manage Power Failure? (2.5”SSD R Series)