Stable SSD Performance In Unstable Power Supply Situations

Supplier: ICP Electronics
03 June, 2021

Power source instability and sudden power loss have always been a challenge for storage devices.

Introduction

Power source instability and sudden power loss have always been a challenge for storage devices. The sudden drop in the power supply can cause data corruption, and in the worst case, lead to total device failure. For this reason, most SSDs for critical applications come with emergency functions that save data and assure that no issues occur when restarting after a sudden power loss.

These technologies are mainly in place to ensure data integrity after an incident has happened. There are, however, other power supply factors that can impact SSD data integrity. Certain applications operate in conditions where power supply is unstable. During start-up and use the voltage might fluctuate, which in turn can interfere with SSD operation and also damage the device. Another significant risk is residual voltage after shutting down. This can further cause issues when restarting the system.

There are, however, preventive measures that can help mitigate these issues. Safeguards can be implemented by optimizing the hardware structure – allowing the SSD to prevent data corruption, damage, and sudden restart issues. This paper will further explain the risks of power loss and power instability, and more importantly, what can be done to avoid these risks.

 

Background 

Power instability is mainly seen in systems with poor and unstable power supply. This istrue for applications such as in-vehicle computers, remote installations, and devices used in under-developed areas where the power grid is less reliable.

However, even in areas where the power supply is stable, power loss can still happen due to unforeseen circumstances. Construction work or a lightning strike is all it takes for the grid to momentarily go down. So even though the risk is lower, mission-critical data still requires data integrity measures.

 

Challenges 

Start-up instability 

There are two risks associated with system start-up: unpredictable ramp-up time and power supply instability.

The SSD will only start after crossing a pre-set threshold voltage. This can cause problems when the ramp-up time takes too long, as the threshold voltage is not sufficient for the SSD. The ramp-up time is dependent on the local power supply situation, and will therefore vary from place to place (see graph 1), making it hard for the manufacturer to come up with a design that takes this variation into account.

During ramp-up, the voltage might fluctuate (see graph 2). This can trigger SSD start-up, but the voltage might continue fluctuating before eventually stabilizing. As with the slow ramp-up time described above, this scenario can cause issues with device start-up and potentially lead to data corruption and damage to the SSD.

Residual Voltage 

There are two risks associated with system start-up: unpredictable ramp-up time and power supply instability.

The SSD will only start after crossing a pre-set threshold voltage. This can cause problems when the ramp-up time takes too long, as the threshold voltage is not sufficient for the SSD. The ramp-up time is dependent on the local power supply situation, and will therefore vary from place to place (see graph 1), making it hard for the manufacturer to come up with a design that takes this variation into account.

 

Solutions

Ramp-up Buffer 

The SSD will only start after crossing a pre-set threshold voltage. This can cause problems when the ramp-up time takes too long, as the threshold voltage is not sufficient for the SSD. The ramp-up time is dependent on the local power supply situation, and will therefore vary from place to place (see graph 1), making it hard for the manufacturer to come up with a design that takes this variation into account.

Start-up without Residual Voltage Interference

Residual voltage can cause issues during SSD start-up. If there are any residual voltage after shut-down, the SSD will force it down close to 0V before allowing a system restart. This safeguard is always in place ensuring safe startup every time, further increasing the SSD’s preventive power protection.

 

Conclusion 

An unstable power supply is a huge risk factor for any device using flash memory. Algorithms for safe shut-down has been available for a long time, but not many are aware of the preventive measures available to ensure a safer power on and power off, as well as a more stable performance.

Efficient power protection measures can safeguard any SSD from unstable and fluctuating voltage – allowing for greater data integrity and a more efficiently run system.