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???
12/15/06 01:58
Modified:
  12/15/06 02:25
Read: times


 		 #129514 - Ok, try this:
Responding to: ???'s previous message
1. Exchange the DS275 by DS276:

http://datasheets.maxim-ic.com/en/ds/DS276.pdf


2. Exchange the LM78L05 by a LP2950CZ-3.3:

http://cache.national.com/ds/LP/LP2950.pdf

Select the regulator for showing an output voltage of at least 3.25V!
Connect an electrolytic capacitor of 47µF/16V directly at input of LP2950. You can put a 100n/X7R ceramics in parallel. But avoid tantals here!
Exchange the power supply decoupling caps at the output of LP2950 by the following arrangement: One 4.7µF/16V tantal must be located closest to the output pin of LP2950! Another 4.7µF/16V tantal should sit at the supply pins DS276. Don't use different caps for them! At supply pins of AT89C2051 connect a 100nF/X7R ceramics. Don't use a "better" cap here!
The tantals must be very tiny (beads) and must be soldered into the board with very shortest leads!


3. Exchange the DS1833 by a DS1817-5:

http://datasheets.maxim-ic.com/en/ds/DS1817.pdf

Take note, that the pin assignment is different!!! Add a 4k7 pull-up resistor to the reset line.

4. If the heat dissipation of LP2950 is high, means if the LP2950 becomes hot, decrease its input voltage by inserting three 1N4004 diodes (or a suited 1.3W zener) between 9V line of battery and input pin of LP2950.

Kai

List of 51 messages in thread
TopicAuthorDate
My two cents and then sum            01/01/70 00:00      
   RC reset - asking for trouble!            01/01/70 00:00      
   be careful now ... here be dragons            01/01/70 00:00      
   May we...            01/01/70 00:00      
      yes            01/01/70 00:00      
   Why you should use a proper reset chip            01/01/70 00:00      
      what about bidirectional reset?            01/01/70 00:00      
         I use only external watchdog / brown-out detection            01/01/70 00:00      
            I doubt this.....            01/01/70 00:00      
               If it really, really has to work..            01/01/70 00:00      
            there isn't much you can do about internal reset            01/01/70 00:00      
               which chip is that?            01/01/70 00:00      
                  DS89C4x0, among, I suspect, others            01/01/70 00:00      
               Micro isn't allowed to emit reset signal            01/01/70 00:00      
         easy as apple pie            01/01/70 00:00      
            Only because it worked for you does not mean...            01/01/70 00:00      
               that does not matter            01/01/70 00:00      
                  Of course, it does            01/01/70 00:00      
   all posts in this thread are incomplete            01/01/70 00:00      
      Then, please read again what I wrote            01/01/70 00:00      
         OK, you had that too            01/01/70 00:00      
         Thanks to all who give comments            01/01/70 00:00      
            What kind of supply regulation?            01/01/70 00:00      
               Battery            01/01/70 00:00      
                  Hhm, I'm confused now...            01/01/70 00:00      
                     Right            01/01/70 00:00      
                        if you specified            01/01/70 00:00      
                           I guess a LM78L05 was originally built-in            01/01/70 00:00      
                        Then, the DS275 won't work either            01/01/70 00:00      
            MAX6383            01/01/70 00:00      
   Maybe here            01/01/70 00:00      
      I did look their first            01/01/70 00:00      
         that is not what you asked            01/01/70 00:00      
            Sorry Erik            01/01/70 00:00      
               read the datasheet            01/01/70 00:00      
                  What photo?            01/01/70 00:00      
                     OOPS            01/01/70 00:00      
                        Always...            01/01/70 00:00      
                           I would like change ds275            01/01/70 00:00      
                              You can, but..            01/01/70 00:00      
                                 Ok, try this:            01/01/70 00:00      
                                    to Kai            01/01/70 00:00      
                                       Only to avoid damage caused by inrush currents            01/01/70 00:00      
                                          Ah, thanks            01/01/70 00:00      
                                          When you say "damage"            01/01/70 00:00      
                        Sorry Erik            01/01/70 00:00      
                           Would it be just too much of an effort for you            01/01/70 00:00      
                              You are right Erik            01/01/70 00:00      
                                 I do, ONCE            01/01/70 00:00      
                                    Erik I said was sorry two times            01/01/70 00:00      
                                       i am not asking for 'sorry'            01/01/70 00:00      

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