Welcome to a new Voltlog, this will be a rather short video cause I will only be addressing one short subject regarding the Riden RD6006 ripple noise. In my review of this power supply in Voltlog #284 I did measure the output ripple but that was measured while using a transformer to power the unit.
That transformer has very little output noise so the results we obtain can be considered best case scenarios but this may vary in practice, especially if you are using the recommended switch mode power supply. The output of that power supply may not be as clean as the one from the transformer so in this video I’m going to measure the output noise with the switch mode power supply installed.
I’m using the recommended NVVV 400W 60V 6.6A rated power supply, this is what RuiDeng officially recommends to use with their power supply kit. In Voltlog 284 part 3 I took a look inside this power supply so I will link that video on screen if you want to check it out.
Welcome to a new Voltlog, if you’ve been watching the channel for a while you might know I’m a fan of the gopher power supply units, I think they are great value for money, they’re simple and they have good specs, in fact I reviewed their latest revision in Voltlog #255 and it had very low noise at the output, even though it is a switch mode power supply. They’re pretty compact, they don’t take up much space on the bench so what’s there not to like about these?
But in recent years there’s been another company which has slowly built-up a name among hobbyists due to their really low priced power supply modules, the name of the company is RuiDeng and they’ve been selling these compact switch mode power supply modules for $20 to $30 for years. They were not great specs, the quality was not great, you needed an external power supply unit but they had a bunch of functionality built into that color TFT display and they were cheap so everyone gave them a try
Now RuiDeng has developed and released a new model RD6006 which resembles a real bench power supply. It has a bigger front panel and it comes with a separate enclosure and power supply unit which are optional.
Welcome to a new Voltlog, in this video we are taking a look at the TPS62840 ultra low power step down converter from Texas Instruments. It’s basically a buck converter with an input voltage of 1.8-6.5V, 750mA output current, with a quiescent current of just 60nA and active current of just 120nA. It also features very good efficiency at light loads of just 1uA it can offer 80 percent efficiency.
Other features include 16 selectable output voltages through an external resistor and a stop pin which when activated will completely stop any switching to eliminate any switching noise for a short moment, allowing you to take for example an ultra low noise measurement during that time. During that take power will be sourced from the output capacitors. So it looks like this is a pretty interesting dc-dc converter, with really nice features and it’s optimized for ultra low power devices.
Welcome to a new Voltlog, those who have been with me since the beginning of this channel, may know the first video I ever released, Voltlog #1 was a review of a switch mode bench power supply from Gopher Technology. It was the CPS-3205C and it was a great little unit, it has served me well over the years and I still have it.
At that time I complained about the fact that the unit has the output jacks on the back which is not really convenient for bench use. There were also other issues mentioned while measuring the performance of the power supply, I will link that video on screen if you want to watch it but the video, audio and editing quality are lower than what you’re seeing today.
Gophert made some improvements to the original design and have now released a newer version of that power supply, it has a new model number it’s NPS-1601 but it’s the same range of 0-32V and 0-5A. There are other models with different ranges but this is what would correspond to the CPS3205 I reviewed years ago.
They have made a bunch of changes on the front panel, the most important one is they moved the output jacks to the front panel so now it’s easier to connect the output of this power supply but they are still not standard spacing so you can’t connect one of these adapters with banana jacks. They have also redesigned the front panel completely, they are still using 7 segment displays but now they also have a wattage display which can be switched on temporarily in place of the amps display, you press the watts button and it will show watts measurement for about 3 seconds before reverting to amps display.
The switch for A/V adjustment is now tactile instead of a sliding switch but the rest has stayed the same. I like this redesigned front panel I just wished they used a lighter color for the text, because for example there are some markings which are barely visible next to the LEDs.
Here is a set of pictures I captured during the teardown:
In the previous video where I took a closer look at the TPS61088, I did some measurements of the output noise but I also ran the module up to the maximum specified output power of 12V 2A. It was to be expected that the losses would turn into heat and just the small size of the board would not be enough to dissipate all that heat safely so the boost chip reached a toasty 150 degrees Celsius and inevitably went into thermal protection.
There were two questions that people mainly left in the comments of that video. First people were curious if this module would behave differently if a heatsink was installed and also some people thought about using this module in a fixed configuration, because if you remember there is a chip on this module that will switch the output voltage based on quick charge spec, depending on what the load is requesting through that protocol but people might just want a simple fixed output. To this I would add a third question of my own, what is the real efficiency figure of this module, at the maximum output.
The real limitation for this small module to output the claimed 24W for longer periods of time is temperature. There is not enough thermal dissipation happening with this small pcb. Having a bigger pcb with more copper layers would help and it would probably allow this module to output continuously and prevent the TI controller chip from going into thermal overload. Even so I was impressed that running it into thermal protection several times did not do any damage the chip recovered on it’s own each time and no magic smoke escaped during these tests.
So all of this considered, this is probably one of the best dc-dc boost converter modules I got from China so far and I would recommend getting one of these if the specs meet your needs.
In the review video, due to an error in my measurement setup I got erroneous values for the output noise. In this video I am re-doing those measurements for the output noise.
