Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Thats a little better. the 3 transistor have more base drive. The TL494 uses 70 of 250mA max and three 2904s use up to 350mA of 600mA max for an effective gain of 5 max and effective net Rce of 2/3Ω in addition to DCR(L)=0.35Ω for a total of 1Ω where the feedback lowers the Zout to improve load regulation error, but then the current sense R adds 2Ω to degrade it.
1) Can you redirect the feedback from output , instead of before Isense drop of 0~0.7V?
2) Will there be a capacitive load that may false trip foldback?
3) Your clock RC is floating and should be grounded.
4) If you wanted faster startup clock, you would use 1nF to gnd and 1nF to Vref so it reaches Vref/2 on powerup and starts clocking immediately.
Yes,I am looking at this improved spec. sheet. It has some useful PCB layout tips for EMI suppression.
https://www.ti.com/lit/ds/symlink/tl494.pdf
DTC soft start seems simple to add at 180Khz as it only requires a 0.1uF cap/ 2.7K combo for 50 cycles start.
I have noticed that most TL494 sample circuits driving a PNP switch include a pullup base resistor at about 1/3rd the value of the base drive resistor. Have a look at figure 15. They mention discharging carriers for proper switching. Does this mean that the transistor is hovering a long time in linear mode without that kind of pullup?