SG Power supply tear down

[flip9]

I wanted to check out my unused power supply that came with the cam so i opened it up.

The plastic case is either glued or ultrasonically welded but a little nudge from a vice loosened it up. Once its opened up you'll see two big capacitors and an inductor. If you turn it around you will see the 8pin regulator and supporting components. I searched the datasheet for the regulator chip and its rated for 24v 2Amps with operating temps of -40 to +85c.

It looks like a good power supply thats well filtered. The 5v output has at least 3 capacitors and ferrite beads (FB) on top of the reference design. The 12v input has 2 capacitors and a bead. (Different sized capacitors filter out different frequencies)

Feedback Pin has a resistor divider (R1 - 47.5k , R2 - 10k) which sets the Output voltage to 5.31v. It will be closer to 5.2v after the voltage drop from the 3m cable length.

Things of note:
-The wires of the USB cable is coloured incorrectly (but pinned correctly)
-I was expecting a diode on the input but a zero ohm link was used instead, possibly as a fusible resistor.
-Component number labels wont match ref schematic (board is used for other applications)
-Cig plug has a 3AG fuse rated at 1A

Ive obscured the chip and board info. The Red line is the output side after the inductor.

 

[jokiin]

we've been using this supply for about a year or so now, we changed the power supply four times prior to this one, it has been very reliable for us to date

 

[SawMaster]

Much better than the cheap junk usually supplied with most cams The soldering of the external wires could be better, but I've seen worse and at least they aren't 'cold' joints, but well bonded.

Just more proof of SG's focus on quality and consumer value

Phil

 

[Deleted member 46308]

Just more proof of SG's focus on quality and consumer value

Phil

+1

 

[flip9]

So I did some load testing on the SG supply and used a 10 ohm resistor to simulate a 500mA~ constant load. A single channel dashcam typically draws around 200-300mA.

The SG had a reading of 5.33v with no load and dropped to 5.19v with the load, which is not bad. As long as its stays above 5v under load the cam will be happy.

Efficiency is 82% (12v to 5v). I did a temperature test after 30mins with a thermacouple to the chip and it reached 47c, from room temp.

-

I did a similar test to a few buck regulators i had lying around:

The LM2596 with the output also set to 5.33v. It took the load no worries, only dropped to 5.30v. Efficiency at 77%

The MP1584 sagged down to 5.10v due to its tiny components but efficiency was at 85%

Also had a hefty sized regulator, cant remember the chip as i put a heatsink over it but it handled the 500mA without blinking an eye and efficiency at 82%.