I was studying the L298 datasheet and I noticed something;
So basically an H-bridge contains two PNP and two NPN transistors as shown in the image:
but in the datasheet, there are no PNP transistors used. There were some tutorials out there on how to make an H-bridge with only NPN transistors but the L298 circuit doesn't look like any of them:
What am I missing here?
Best Answer
In your H-bridge schematic, the same signal is being used to drive the bases for the upper and lower transistors. Because the top ones are PNP, and the bottom are NPN, the tops will conduct when the signal is low, and the bottoms will conduct when the signal is high.
The L298 schematic shows that inputs for the lower pair are inverted. That's the little circle in the inputs to the AND gates. So even though the tops and bottoms are all NPN, the tops and bottoms will still conduct at opposite times.
The schematic is correct.