| Electronics > Projects, Designs, and Technical Stuff |
| TL 494 feedback loop doubt |
| (1/1) |
| Achu:
Hi Im tying to make a boost converter circuit.All the designs based on tl494 are shown to have positive feedback. In my knowledge in if the o/p voltage increases feedback increases and pwm duty cycle will also increase and this will cause a domino effect. Maxim website shows a negative feedback loop. Im confused please correct me guys. |
| dietert1:
From Fig. 9 of the TI TL494 datasheet you can understand that the input + and - denomination is unusual. The schematic you have appears to be correct. They exchanged the two comparators for current and voltage but that shouldn't matter. Regards, Dieter |
| T3sl4co1l:
Right, the output is inverting (see the pair of NOR gates). Or inverting again depending on if you use the C or E pins as output, and with an inverting driver (as shown here) or not. Tim |
| Cliff Matthews:
It would seem RV1 in that voltage-sense divider could seriously do harm to the TL494.. |
| xavier60:
The way that the OR-ing diodes are wired means that whichever op-amp's output is the highest will take control of the PWM, reducing it. The op-amps need to be configured as non-inverting. The output phasing has to also be correct. When the TL494's transistors are on, the switching element should also be turned on. |
| Navigation |
| Message Index |