New PWM FAN controlers with speaker protection module

On the previous post I wrote about modular amplifier, can be connected to single, parallelled, and bridged mode (here is the PDF manual). The single amplifier is about 75-100W, bit with parallel and bridged mode the full poweramp maybe 700-800W (with bridged mode, but with 3 paralleled module). The original design contains one module for speaker protection with UPC1237 chip, which is very cheap and good solution. But the FAN controller for thermal protection is missing.

The thermal protection included to all TDA7293 chip, but no fan controller. The benefit of PWM FAN controller is the control sign is depend on the heatsink heat. I re-designed the PCB of speaker protection with PWM Fan controll circuit, but I made two versions. The first working with 4 OpAmps, and controls 3 fans with 10A output current:



The fan controller starts with 12V regulator, and the end of this circuit the 200V 10A MOSFET before fans. Paralleled with fans I have LED to display the "heat" of the system because the LED controlled with same same output like the fans.

Here is the PCB for this new module which compatible with the original speaker protection module:


This have PCB 7cm width, which is too much, so I looking for smaller and simpler fan controller circuit. Lot of solutions available on the NET with 555 and 556 timer IC, but I made something with MIC502 fan controller circuit. This circuit is simple and "vintage" DIL8 package, not the cheapest solution, but small, and not too much other parts required. The benefit of this solution, that the "sleep mode" setting. This is the threshold while the FANs not working (if not required).



with this simplest circuit I can design smaller PCB:


The width of this PCB is 55 mm instead of 70, what is good result. The speaker protection without PWM fan controller is 51 mm. This module now 4 mm wider.

I have one more choice to made PWM controller. The AMC6821 chip is really good solution. The chip made for computer mainboards, so the size is really small which is not really good for home designers, but maybe more smaller solution is good news for industrial designs.

The AMC6821 PWM Temp monitor and FAN controller chip:


The application of this is really easy and simple. The original module, contains speaker protection only is available if the single version of TDA729x modular amplifier required. But if using more modules for paralleled and bridged application, maybe for real instrument amplifications, the good heating system with temperature monitored FAN controller required.

See also:

• Failure in the official datasheet of TDA7293
• TDA7293 for more than 300W
• Modular TDA7293 bridge/parallel amplifier
• PDF manual for TDA7293 amplifiers

PCB sales of this project Module name Size (mm) Area (cm2) PDF SCH PCB image Tested Price (US$) Des. Sim.1 Full2 Sim.1 Full2 Man3 PWM Fan controller V:1 70x57 40 Yes Yes Yes - - No 7 15 Ask PWM Fan controller V:2 56x57 32 Yes Yes Yes - - No 6 14 Ask How to order? Please read the rules carefully!