Advanced Transient Response Tests

In these tests, we monitor the response of the PSU in two different scenarios. First, a transient load (10 A at +12V, 5 A at 5V, 5 A at 3.3V, and 0.5 A at 5VSB) is applied to the PSU for 200 ms while the latter is working at a 20% load state. In the second scenario, the PSU, while working at 50% load, is hit by the same transient load. We measure the voltage drops that the transient load causes using our oscilloscope for both tests. The voltages should remain within the regulation limits defined by the ATX specification. We must stress here that the above tests are crucial since they simulate transient loads that a PSU is very likely to handle (for example, booting a RAID array, an instant 100% load of CPU/VGAs, etc.) We call these tests "Advanced Transient Response Tests", and they are designed to be very tough to master, especially for PSUs with capacities lower than 500 W.





Deviations at +12V are low on both tests. The same applies to the 5VSB rail and, to a smaller degree, the 5V rail. The 3.3V rail apparently registered the worst performance with a deviation of over 4% and a voltage below 3.2 V during the second test.

Below, you will find the oscilloscope screenshots that we took during Advanced Transient Response Testing.

Transient Response at 20% Load

Transient Response at 50% Load

Turn-On Transient Tests

We measure the response of the PSU in simpler scenarios of transient loads - during the power-on phase of the PSU - in the next set of tests. In the first test, we turn the PSU off and dial the maximum current that the 5VSB can output before switching the PSU on. In the second test, we dial the maximum load that +12V can handle and start the PSU while the PSU is in standby mode. For the last test, while the PSU is completely switched off (we cut off power or switch the PSU's on/off switch off), we dial the maximum load that the +12V rail can handle before switching the PSU on from the loader and restoring power. The ATX specification states that recorded spikes on all rails should not exceed 10% of their nominal values (e.g., +10% for 12V is 13.2V and for 5V is 5.5V).


We didn't measure any spikes or voltage overshoots on any of the above tests, which is great! The rise time was also within the ATX specification in all cases (0.2-20 ms). As you can see, Super Flower left no room for complaints here - quite the opposite.