Undervoltage recovery meaning

[ctiger]

Hi all,

I would like to know what does undervoltage recovery means. I have a compressor driver and under the specifications there are undervoltage protection @ 18V, undervoltage recovery @ 25V.

I understand undervoltage protection is when <18V the driver shut off (correct me if I'm wrong), but I do not understand what does the recovery mean.

Any opinions will be much appreciated.

Thanks in advance.

[ataradov]

Is it possible that 25 V is when it turns back on after turning off in undervoltage condition.

This will make the gap between 18 V and 25 V to be a hysteresis, so there is no constant turning on and off at a crossing point.

[ctiger]

The specifications stated that input voltage range of 18 V ~ 33 V


withstand voltage range < 40 V
undervoltage protection @ 18V
undervoltage recovery @ 25V
overvoltage protection @ 33V
overvoltage recovery @ 30 V

so does that mean that within the range of 18 V to 25 V theres no switching on and off, I just got confuse about the recovery on the datasheet.

Thanks again in advance.

[ataradov]

Yes, it looks like it. So if voltage start raising from 0 V, output will first turn on at 25 V. Then it will be on until 33 V, and which point it will turn off. When voltage starts to drop and drops to 30 V, the output will go back on. And it will stay on until input voltage drops to 18 V.

So whether there is voltage in 18-25 V and 30-33 V bands depends on what side you are approaching the band from.

[ctiger]

Ok that make sense.

Thank you Alex

[Simon]

Take the case of an infinion smart switch, whose datasheet describes very well the reasoning. Say in the case of a smart switch (smart mosfet) you tell it to turn on and power a large load, if the voltage is dragged below the cutoff voltage it shuts down, having turned the output off the input voltage rises again, so it goes again and again trigger the low voltage cut off, the result is that the chip oscillates and overheats, because it keeps restarting the overheat protection can't function properly and it burns out. To prevent this they demand you put a decent amount of capacitance close by. You may have a similar problem but it sounds like they have tried to slow things down with a large hysteresis.