MISC-TN-027 — Qualifying a product for industrial, harsh environments: resilience against power supply anomalies

Info Box

History

Version	Date	Notes
1.0.0	July 2023	First public release

Introduction

Over the decades, DAVE Embedded Systems has been sharpening a tight qualification process for the products the company has been commissioned to design and manufacture. This process is relentlessly engineered to cope with the challenging requirements of industrial applications operating in harsh environments and the ever-increasing complexity of system-on-chips these products are based on.

The qualification process comprises several tests with different characteristics and goals. One of these tests is specifically designed for verifying the resilience of DUT's power supply unit (PSU) to supply voltage anomalies, which are pretty common in industrial environments. This Technical Note (TN for short) describes how we run this test.

Test description

To make this test possible, DAVE Embedded Systems designed an ad hoc smart bench power supply denoted as PPSU. PPSU is used to power the DUT, which is the electronic device under test. You can think of PPSU as a programmable power waveform generator that is also able to verify the health status of the DUT. PPSU can generate an arbitrary supply voltage that exhibits purposely anomalies such as glitches of different duration and non-monotonic ramps. A robust product is expected to be resilient against these stressing conditions. This means that it is supposed not to be affected at all or to perform properly a warm reboot cycle if it is inevitable that a hardware reset is triggered. Of course, the expected behavior strongly depends on the nature and severity of injected anomalies. After the anomaly is injected, PPSU verifies whether the DUT is operating properly or not and logs the test result. PPSU can also be programmed to run the test cycle repeatedly for the desired number of iterations.

TBD

Combining several test waveforms of different types (1) and running these test over the entire DUT's operating temperature range allow to achieve good confidence that the product's PSU will not fail in the field because of "misbehaving" power supplies. Furthermore, these tests are extremely useful to detect hardware design errors or more subtle situations like the one described in this application note by ST Microelectronics. Thank to the use of PPSU, during the qualification of the ETRA Single Board Computer, we were able to spot the issue illustrated in the application note before its publication.