My love for electronics has driven me to pursue a career as a laptop motherboard repair technician. I am also studying to be an electrical engineer. I study diagrams and buy faulty laptop motherboards ( with no power) to fix as a hobby that has turned lucrative. But my skills are not that great though i understand as much as I learned in the past 6 months I still find my self lacking the theory aspect as most of you guys on here got down.

So i come to you with a diagram of the inside of a charging ic from a laptop motherboard. I have spent the past couple of days trying to understand it.


my question is this

comparators and op amps have similar symbols on schematics. so i was wondering on this diagram for the ACIN PIN AND ACOK…is that a comparator or an op amp? ALSO IS THE OUPUT TO ACOK?…from ACIN it seems to go into comparator or op amp looking symbol..than ouput to where? ACOK?

i wanted to start a thread on this diagram to dissect it and understand it better with your help if possible. so lets start off with these two pins ACIN AND ACOK

 

ACIN goes to a Schmidt Trigger. It's like a comparator with a dead spot in the center of its input range. If ACIN has enough amplitude to go higher and lower than the dead range, the trigger outputs a square wave which drives a mosfet, which allows current to pass to ground from the ACOK pin whenever ACIN is more positive than the dead range.

 

so bascially let me try to rephrase it

if acin is higher than 3.2 volts the trigger outputs a square wave that allows current from acok to ground

where is the current coming from for acok? is it an input from outside the chip ?

 

if the ac voltage applied to acin is higher than 3.2 volts plus the hystresis of the Schmidt Trigger input, the trigger outputs a square wave that allows current from acok to ground

where is the current coming from for acok? is it an input from outside the chip ?

Yes. ACOK is just a switch on a ground circuit. You might attach a resistor and an LED to it or you might find another pin of the IC which needs that signal before the chip will start, but you didn't ask about that so I didn't read the whole datasheet. You need to read about the IC to find out if it has a safety lockout that will stop the chip if ACOK is not oscillating.

 

http://pdf1.alldatasheet.com/datasheet-pdf/view/110641/MAXIM/MAX8725ETI.html


heres a simlar chip….looks like acok is asignal sent by the chip to indicate the presence of an acadapter

 

http://datasheets.maximintegrated.com/en/ds/MAX1909-MAX8725.pdf


heres another one i found…seems to be when acin exceeds 2.048v it will send out a signal at ACOK

 

It looks like you need to attach a resistor from "LDO" to "ACOK".