Record system error caused by power supply circuit

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Macnica Engineer

Record system error caused by power supply circuit

There are many cases in which it is difficult to confirm the reproducibility of a system error caused by a power supply circuit that occurred during a trial evaluation before mass production or in the market.

Power failure

It is common to incorporate a mechanism in the circuit that monitors the power supply circuit and raises an alert when there is a system abnormality or power supply abnormality. It's good to monitor the power circuit, but it's very hard to see what kind of problem occurred on which power supply.

In such cases, it is very useful to be able to record the log when an error occurs. Now let's talk about logging solutions.

The power supply circuit is damaged due to overvoltage damage.

If the power supply circuit (IC or module) has an output error due to an overvoltage failure (EOS : Electrical Over Stress), it is easy to identify the problem circuit by checking with a tester. In some cases, it may be burned out and visible (see Figure 1).
In case of frequent occurrences, there is a high possibility that there is a problem in the usage of the power supply IC and the module, so it is a quick way to confirm the usage.

Figure 1 : Appearance of Overvoltage - Destroyed IC

What if there is a power supply circuit failure other than overvoltage break?

If the power supply circuit is abnormal other than overvoltage, I think that the power supply circuit is operating normally even if the defective board is checked.
This is often caused by malfunction due to power supply circuit or ground wiring pattern.

Even if the operation verification is carried out for a long time in order to reproduce the failure related to the power supply circuit other than the overvoltage breakdown, it often becomes non - reproduction.

Solution for logging power circuit faults

Analog Devices has a product called Power System Management (PSM).

The LTC2977 of the PSM product can be connected to the DC/DC converter as shown in Fig. 2 to adjust the voltage accuracy to ± 0.5% or to control the power supply sequence.
Since it is possible to set up a power sequence by controlling the power supply voltage precision with high precision or by changing the built - in register setting with the GUI, it has a very high affinity with the board equipped with the FPGA.
Another characteristic function is to detect an error in the power supply circuit.

Figure 2 : LTC2977 Connection Example and Power Sequence

Ability to detect and log power circuit faults

The PSM is capable of detecting an over voltage / under voltage / over current condition with a high speed comparator of 10 u sec.

The error in the power supply circuit detected by this high - speed comparator is automatically saved in the EEPROM inside the PSM. This logged log is useful when a system is withdrawn from the market due to a power circuit fault.

Normally, it is difficult to reproduce the abnormal condition, and it is also difficult to confirm which power supply circuit caused the problem. However, if the board is equipped with a PSM, it is possible to read the error log using a free tool dedicated to the PSM (Figure 3).

By checking this log, you can check the date and time of occurrence, the monitored voltage value, and the error content. This will allow us to quickly create reports on market failures and report them internally and to customers.

Figure 3 : Sample Recorded Log

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