Delkin Blog

“Our flagship product is bricking across our entire customer base, help!”

A manufacturer of hand held devices called us in a panic one day over an SD card failure that was causing their flagship product to brick at an alarming rate.  Irritated customers were reporting data corruption in the field and threatening to cancel all orders, and the team working to address and fix the issue couldn’t get any support from their existing memory card supplier.

Customer Story

“It all began six months ago when Marketing asked if we could extend the battery life of our flagship handheld device. This device was our best selling and most profitable core product, and the lead device of our entire product line. It was estimated that a power improvement could increase our market share by up to 3% and make 2016 our most profitable year yet.”

After some exploration, we discovered that if we turned off the power to the SD card, we could reduce the overall power usage and extend the battery life between charges. The change was made to our application and tested, and a small power saving was achieved – we were thrilled! The change was implemented on all units and we were able to launch with an improved power rating.

Shortly after launch we received a call from one of our largest and oldest customers, reporting hundreds of failures in the field. Not only was this customer threatening to cancel all open orders and return the product they had, they had also decided to begin searching for an alternate supplier.”

Delkin Discovery

The manufacturer of the bricked handheld device called Delkin’s Customer Applications Team to help them get to the bottom of the issue. Right away we went to work to understand the usage model and capture bus activity between the host and the card. While the cards seemed to be corrupted, it was at a random interval and we needed to understand why.

After further discovery, we learned that the SD card data corruption was a result of the power saving software change that was implemented just prior to launch.  While the power to the card was “turned off”, the customer didn’t realize that the card could still draw just enough power to stay alive from leakage on signal pins. The small power leakage was enough to keep the CPU alive and perform housekeeping functions, but when any type of write operation was attempted, the power immediately dropped and caused flash write errors.

Delkin Solution

Rather than simply “turning off” the power to the SD card, Delkin recommended that the customer modify their application to drive each of the signal pins low, prior to turning off the power. Not only would this fix solve the data corruption issue, it also had the potential to save even more power by preventing leakage after the main device power was turned off.

The customer was ecstatic, and was able to make a quick update to their application software. After the new code was loaded and tested, all units were updated within a few days and shipped out to their customer base. Confidence was restored, and their stable revenue stream was saved.

Lesson Learned

It’s important to remember that a NAND flash memory card is much more complicated than just a “memory chip”. In this scenario where degraded power was an issue, flash writes were misinterpreted and data was sent to the wrong spot in flash.

Lean on Delkin’s Technical Team

Have you had a problem with your host storage?  The Delkin Customer Applications Team stands at the ready to be your trusted advisor for your host critical storage.  We have solved hundreds of complicated host failures and look forward to understanding your usage model for flash based Rugged Controlled Storage.