Transient Response Tests
Advanced Transient Response Tests
For details on our transient response testing, please click here.
In these tests, we monitor the response of the PSU in two different scenarios. First, a transient load (10A at +12V, 5A at 5V, 5A at 3.3V and 0.5A at 5VSB) is applied for 200ms while the PSU works at 20 percent load. In the second scenario, the PSU is hit by the same transient load while operating at 50 percent load. In both tests, we used our oscilloscope to measure the voltage drops caused by the load. The voltages should remain within the ATX specification's regulation limits.
These tests are crucial because they simulate the transient loads a PSU is likely to handle (such as booting a RAID array or an instant 100 percent load of CPU/GPUs). We call these tests "Advanced Transient Response Tests," and they are designed to be very tough to master, especially for a PSU with a capacity of less than 500W.
Advanced Transient Response at 20 Percent
Advanced Transient Response at 50 Percent
Super Flower's Leadex platform responds impressively to transient loads. At +12V, the deviations in both tests are minimal; the same applies to the 5VSB rail. Deviations on the 5V rail stay within 2 percent, and the 3.3V rail manages to stay within 2.5 percent (a very good performance for this rail). All in all, the 850 P2 performs well, especially on that crucial +12V rail.
Here are the oscilloscope screenshots we took during Advanced Transient Response Testing:
Transient Response At 20 Percent Load
Transient Response At 50 Percent Load
Turn-On Transient Tests
In the next set of tests, we measure the response of the PSU in simpler transient load scenarios—during the PSU's power-on phase.
For the first measurement, we turn off the PSU, dial in the maximum current the 5VSB rail can output and switch on the PSU. In the second test, we dial in the maximum load the +12V rail can handle and start the PSU while it's in standby mode. In the last test, while the PSU is completely switched off (we cut off the power or switch off the PSU by flipping its on/off switch), we dial the maximum load the +12V rail can handle before switching on the PSU from the loader and restoring power. The ATX specification states that recorded spikes on all rails should not exceed 10 percent of their nominal values (+10 percent for 12V is 13.2V, and 5.5V for 5V).
All slopes ramp up smoothly, and as you can see there are no voltage overshoots or spikes. Great performance overall!