I just received a Topshak LW-3010EC programmable power supply. Like many cheap lab power supplies out there, this is yet another re-branded power supply that uses the main power supply board designed by Longwei. In this blog post, I will share some of the teardown pictures from this power supply and a similar power supply I did a teardown with a few months back.
This Topshak power supply has a dimension of 7cm x 15cm x 21cm, which is rather compact considering that it is capable of delivering a maximum output of 32V at 10.5A. I like this form factor a lot as the power supply can be easily tucked away between other test gear.
Upon opening up the case, you can see the main switching power supply board below.
Similar switching power supply circuit board design can be found in many of the popular 30V 10A lab power supplies in the market. For instance, you can see the main board from this Topshak power supply (LW-3010EC) and a Kaiweets power supply (PS-3010F) below. The one to the left is from the Topshak and the one on the right is from the Kaiweets.
The main switching controller is an SG3525A PWM controller chip on the secondary of the main pulse transformer. And there is a separate TNY280GN switcher for powering the auxiliary circuit.
The reverse side of the board is almost identical as well (Topshak to the left, Kaiweets to the right). There are some slight differences between the placement of of a few components. For instance on the Kaiweets board one of the power resistors is soldered on the other side of the board and one of the capacitors is bodged on the bottom side. Otherwise, these boards are largely identical.
The main difference between these two boards is the placement of the 5V rail circuitry for the USB charger port. In the Topshak, this circuitry is separated out onto another PCB whereas in the Kaiweets, it is in a section on the main PCB. The 5V rail is powered by yet another switcher chip DK112.
A key difference between the Kaiweets and the Topshak is that Topshak is programmable. And this is achieved via an additional digital control board mounted behind the front panel as seen below.
The main chip is an STC 15F2K60S2 which has builtin ADC and PWM control for DAC. The programmed voltage/current settings are stored in the EEPROM shown to the right.
The shift registers (74HC595D) are likely used to drive the 7 Segment displays. Two linear regulators are used to generate the postive and negative 5V rails which are used to power the LM358 OpAmps.
You can check out my video review of this Topshak LW-3010EC programmable power supply on YouTube below. In this video I also demonstrated the power on and overload protection characteristics of this power supply.
Here is a link to my review of the Kaiweets power supply I mentioned in this post.