DS276 datasheet(4/11 Pages) DALLAS

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DS276

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two similar devices over short distances, and into larger loads than the 3 k

Ω=RS-232 standard (Figure 2).

If Vdrv+ is increased to 5V, and Vdrv- decreased (to less than -2V) communication with standard RS-232

devices is possible, although of course the output voltage swing of the DS276 remains below the RS-232

specification. The Vdrv- supply can be derived using the “stealing” technique shown in Figure 4.

5V OPERATION

The use of a single 5V supply for VCC and Vdrv+, and Vdrv- derived using the circuit in Figure 4 can

produce reliable communication with standard RS-232 devices, although the DS276 output voltage

swings are below the RS-232 minimum (Figure 3).

Increasing the magnitude of the voltage to Vdrv+ to 10 volts or more will result in “true” RS-232 output

voltage levels.

SINGLE 3V OPERATION Figure 2

(See Note 3)

SINGLE 5V OPERATION Figure 3

(not true RS-232)

(See Note 1 and 3)

"STEALING" NEGATIVE SUPPLY Figure 4

(See Note 2)

DS276 Datasheet(PDF) 4 Page - Dallas Semiconductor