I'm trying to understand how does UCC28703 PWM-controller work. But I don't understand what do the following pictures mean:

E/A comparator


comparator with hysteresis.

I know they are comparators, but I don't know what does E/A mean and what does the hysteresis stands for.

Could you explain how do they work?


The datasheet is here. The block-diagram is at the page 9.

  • \$\begingroup\$ E/A is error Amplifier. It's the main difference amplifier in the control loop and usually the loop is compensated around the E/A. Hysteresis is very common in electronics. A good explanation can be found easily in Google or Wikipedia. \$\endgroup\$ – akellyirl Mar 21 '15 at 14:21

E/A stands for Error Amplifier. The inputs to this amplifier are a reference voltage and a sample of the output voltage. The difference between these two voltages is the error and the amplifier takes that difference, amplifies it and sends it to the control circuitry which will adjust the output voltage in the direction to make the error zero. The sample of the output voltage is also fed to a comparator; the other input of the comparator is a voltage proportional to the overvoltage setting. If the output voltage exceeds the overvoltage setting, this comparator will flip states and its output will be used to shut down the regulator. The symbol inside the comparator symbol does stand for hysteresis. Hysteresis means that the switching thresholds to turn the comparator on and off are not equal. A small voltage difference is required which helps to prevent the comparator from oscillating when its 2 inputs are almost at the same voltage.

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