I have a Address Select pins (A0, A1, A2) for I2C Serial EEPROM. These 3 lines enables 8 different addresses for IC. What I want is to connect these lines to DIP switch, so I can manually change addresses. Can I connect those lines from dipswitch directly to GND and VCC or I need pull-up/pull-down resistors?


Either use pull-up resistors and use the DIP switches to pull down to ground, or use pull-down resistors and use the DIP switches to pull up to Vcc.


simulate this circuit – Schematic created using CircuitLab

If you do not pull (up|down) the address lines will be floating when the switch is open, which means arbitrary addresses will be in effect due to noise on the open, typically high-impedance address sense lines.

  • \$\begingroup\$ Well, that depends on the specific IC. Some are fine with floating address pins. \$\endgroup\$ – Passerby Jun 27 '13 at 20:42
  • \$\begingroup\$ @Passerby Generic question, hence most generally applicable answer. \$\endgroup\$ – Anindo Ghosh Jun 28 '13 at 2:42

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