Tibbit Power Lines

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By now you know that the main supply voltage for Tibbits is +5V, and that some Tibbits also need +15V and -15V power. You also know that C1 Tibbits have no standard ground and +5V pins, while C2s do not have a provision for -15V power. Finally, you know that some Tibbits do not require any power. This section continues with the explanation of Tibbit power lines.

 

power_scheme

 

The diagram above shows five Tibbits. Two of them are #10 (+5V power supply), one is #01 (four-line RS232 port), another one is #12 (+15/-15V power supply), and the last one is #13 (the ADC converter).

Notice how all five Tibbits have diodes in their power lines. On power consuming Tibbits (#01, #13) these diodes prevent damage to Tibbits if power is accidentally applied in reverse. On power generating Tibbits (#10, #12) the diodes allow you to bank power sources. By having two power supply Tibbits (#10) you can either combine their current output or increase reliability (by having several redundant power sources).

Power, of course, can also be applied to the power rails externally (i.e. from a lab power supply). Our own TPP2 and TPP3 boards have power terminals for direct 5V power input. The boards do not have direct inputs for +15V and -15V. So, although TPP2 and TPP3 have +15V and -15V power rails, the only way to have power on them is to insert the Tibbit #12. You only have to do it if there are any Tibbits in your system that require these optional voltages. On the above diagram, Tibbit #13 does require +/-15V.

One additional point. Power supply Tibbits that provide +5V power generate it from external power sources. For example, Tibbit #10 takes DC input in the 9-18V range, while Tibbit #23 implements PoE (power-over-Ethernet) power supply. Both take external power and convert it into +5V. Tibbit #12, however, generates +15/-15V voltages form the 5V power rail.