Eventuelle Ausgleichströme, falls doch vorhanden, kann man sicher mit Schottky-Dioden (D1, D2, D3) ganz eliminieren:
Code:
                            D1
                 .-------.
               +-|MAX1811|-->S--+
               | '-------'      |
               |     |          |
               |    ===         |
               |    GND         |
               |            D2  |
               | .-------.      |
         >-----+-|MAX1811|-->S--+----+
               | '-------'      |    |+
     USB       |     |          |    -
     5 V       |    ===         |   --- Akku
               |    GND         |    |-
         >-+   |            D3  |   ===
           |   | .-------.      |   GND
          ===  +-|MAX1811|-->S--+
          GND    '-------'
                     |
                    ===
                    GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)