While I was learning How to Design 12V DC to 220V AC Inverter Circuit using TL494, I came across another similar PWM controller which is the SG3526. I think I found it in older PC power supply unit (PSU) and searched for spare part, but I did not find it. However, I wanted to know the difference between these two PWM controllers for DIY inverter design. So, I researched for a while about these two ICs and write down note about it.
I found that both of them are extremely popular in power electronics circuit, espcially in inverter circuits. I also found that comparing the TL494 and the SG3525 (which is the modern, more popular sibling of the older SG3526) is still a classic debate.
1. Popularity: The TL494 is the "King"
The TL494 is arguably the most popular PWM controller in history.
Why: It has been the "heart" of millions of ATX PC power supplies for decades. Because they are produced in such massive quantities, they are incredibly cheap and available in every local electronics shop.
Community Support: If you search for "DIY Inverter," 80% of the circuits you find will use the TL494. This makes it better for beginners because there is so much troubleshooting help available.
2. Performance & Features: The SG3525/3526 is "Better"
While the TL494 is more common, the SG3525 (and its relative, the 3526) is technically more advanced for high-power inverter designs.
| Feature | TL494 | SG3525 / SG3526 |
| Output Drive | Open-collector (needs external transistors/totem pole). | Totem-pole output (can drive MOSFETs directly). |
| Shutdown | Needs external circuitry to pull DTC high. | Dedicated Shutdown Pin for fast protection. |
| Soft Start | Must be hacked using the DTC pin. | Built-in Soft Start capacitor pin. |
| Under-Voltage Lockout | No (can behave weirdly as battery dies). | Yes (shuts down safely if voltage drops). |
3. Which one should you use?
Use the TL494 if:
You want to follow the most common tutorials online.
You are salvaging parts from old power supplies.
You enjoy building the external driver stages, like the BC327 totem pole(like in the schematic in DIY 12V DC to 220V AC Inverter using TL494 PWM) because it helps you understand the circuit better.
Use the SG3525 / 3526 if:
You want a cleaner, more compact PCB design. Since it can drive MOSFET gates directly (up to 200mA–500mA), you can often remove those extra driver transistors.
You are building a high-power inverter where safety features like Under-Voltage Lockout and Soft Start are critical to prevent blowing up expensive MOSFETs.
