DATASHEET MAX1632 PDF

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Goodbye Lorita, wherever you’ve gone If the battery is removed then after a while it will boot successfully from the mains and is fine.

T20 Blink Of Death Circuit Questions – Thinkpads Forum

However if the battery is inserted then no boot, only the BOD and it no longer boots with the mains either regardless of whether the battery is in datasheft not. Mzx1632 or twice it did boot from the battery solely and worked for an hour or so until it switched itself off. It was long enough to get a CPU temperature and battery monitoring program to run. Besides the FAN works ok anyway.

Also I bought a new battery for it and repleced the bios battery and ran memory tests using PC doctor repeatedly and all passed even while shaking the laptop around in the air. I removed the motherboard and touched up all inductors and caps on both sides but no joy still so I checked out the circuit having seen some posts about various voltage control ICs.

These two ICs require a high voltage on their SD pin in order to start running. My question is does anybody know where these pins are fed from? It must be some kind of logic or RC circuit coming from the Power On button but which components I do not know. The MAX must be told to raise the 5v and 3. It seems that you have documented this issue a little bit more than anybody else around here.

MAX1632 Datasheet PDF

Both the T21 and T22 that I have with the BoD problem never shut down by themselves; they seemed to work fine until I powered them off and then crossed my fingers and tried turning them on again. Sometime they would work, mostly they did not. The T22 I have had without power for several weeks still does not power up no matter if I use a battery only, AC only or both. Your circuit diagnostic appears to be sound. A defective RC network could indeed be the ultimate problem so check the resistors as well.

The only advice I have would be to trace back from those two MAX pins and see where they lead. Not an easy thing to do when the circuit schematics are not available.

All links to PC-Doctor software hosted by me are dead. So, thanks a lot for the above contribution, wireman. Especially, that about the temperatures releaves me for a lot of speculations.

For myselves, I have the problem with a T21 board. The last time I had the board out I got interrupted, but it is still on my ‘to do’ list.

I have already replaced the board with a working one, but somehow, I just cannot let the problem go – I have to know why. I made my first notes on this board in marchand I still does not know what’s wrong – guess it is about time to get this issue closed. Personally, I do not belive that all machines with these symptoms has the same root datashset. But the varius causes are hidden behinde the fact that the machines does turn off as soon as something datasheeet is happening to any of the power lines coming out of the max Also, the symptoms differs datahseet.

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Ray’s machines does stay on when they do turn on.

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Mine and wireman’s does not stay on. The reason why none or so few of the BOD problems has been solved – I belive – is that it is impossible to measure what is going datasheeh just before the shutdown. It takes approximately 18 milliseconds for a max to shutdown – might well be the same for a max At that speed, a multimeter cannot visualize what is happening.

Neither can an ordinary oscilloscope. A storage-scope might be able to, but then there would be the issue of having the error condition reset. One cannot wait days between each measurement. I hope that no one will disaggre, when I am stating it as a fact, that it is the max chip that is detecting something as an error and initiating the shutdown.

It is the only chip I have found that is capable of turning the machine completely off. By reading the datasheet for the max, I have discovered that maxim actually did anticipate, that it would be impossible for designers to design datqsheet with this chip, as designers would not be able to measure what was going on, if their experiments would not turn out as expected.

For this reason maxim actually made a chip similar to the max, but without the protection circuitry. It is named max One might wonder why maxim did not expected similar problems for repair people! Maxim recommends using max during development and max for production – ibm seems to have followed that recommendation. A side note here – I am currently working on a Toshiba made in It also uses a maxim chip to control the powerup sequencing. The max does have the protection circuitry, the max does not.

The strange thing is that Toshiba designers have not daatasheet the maxim recommendation of using the max in the final product.

The chip actually found in this Toshiba machine is a max – the one without the protection circuitry. I belive that if Toshiba designers had chosen the max for this model, then the machine I am working on, would now be showing the BOD symptoms.

I am convinced that ibm has also used a mixim chip for powerup sequencing in the newer thinkpad models, but I am wondering which one. I just bought a defect T40 on ebay earlier today.

I just have to know which mixim chip is in there. What I think would be necessesary to do, to get further into this problem, is to find a way of disabling this shutdown. Once the protection circuity has been disabled, the real error might reveal itselves by sending out a smoke signal or at least making it possible to do some ordinary voltage measurements within the power circuitry.

It is even possible that the machines will run without any problems, if the shutdowns are only initiated due to a to restrictive protection circuitry. My last experiment was to replace the adp It did not help. But I did notice one thing. While the adp chip was removed, I could get power on the board.

Both the 5V and the 3. My next experiment will be to try to power up the board with the cpu removed. The purpose of the adp is to generate the core voltage for the cpu. Naturally, the indicators normally used to determine the status of the board lcd panel, leds, beeps etc. The status of the board will have to be determined by voltage measurements or similar. I use a laboratory power supply to power the board.

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It has a display showing the amount of current drawn by the board. Enough for me to tell whether the board is on or off. I have a strong feeling that it will be possible to keep the max running by removing the cpu. Last time I was doing measurements on this motherboard, I was using a setup, where I had attached the motherboard directly to a port-replicator. No other thinkpad components involved. The motherboard directly on the port replicator.

Did not even have a fan on the cpu. Just kept an eye on the meter on the power supply and a finger on the cpu, so that I would be warned, should the cpu temperature start rising – which it did not the adp was removed. If only I could find a max, I would try to replace the max in my board with it, just to see what will happen.

In my opinion, it does not matter how the machine is being power when trying to start it up. When the power adapter is attached or the battery is inserted the max will always receive power and therefor it will not reset a previusly detected error condition – even if the error condition has been releaved.

Also, the max will not reset immediately when power sources are removed from the machine, as the capacitors on at least one of the 5V and 3. The datasheet for the max says this clearly. All voltages must disappear before an error condition will be cleared. Concerning the schematics I would say, that I have not really missed them here. The datasheet’s for the max and the adp does contain sample schematics on how these chips are intended to be implemented. And the actual implementation seems to be close enough for the samples to be useful.

My T23 does the same as you guys mention Anyways, guess it wont help to replace the Mobo, since it seems like that the Maxim chip is causing the problem and not just a defect mobo? Or am I wrong T23, T41, T60 and R Even though there are a number of cases with boards that has this problem, it is still just a very small percentage of all boards ever made. Finding a working board should not be a problem. Seems I’m not the only one who can’t leave problems alone. SMA seems to have spent quite a bit of time on this too and thank you for your information.

I had to read it several times as you had so much done already on this. I have done a bit more looking at this and from what I can see the schematic for the ADP on the back page of its datasheet does not agree with the T20 circuit in that the SD pins are not tied together.

However I have tried to lift the SD pin on the to activate VCC Good but am unable to as the pads are very flimsy and am worried it will lift and break.

I have buzzed out the board all over to try and find its source but have been unsuccessful so far. I solved it by this As you have already dismantled the machine, take it as the oppurtunity to clean up all the mating points. Pls leave a feedback.