DS276 datasheet(5/11 Pages) DALLAS

5 / 11 page

DS276

5 of 11

NOTES:

1. This circuit as shown does not meet the RS-232 requirement for signal levels (high-level output

voltage). However, as most RS-232 receivers will interpret any voltage over 2V as a space this will

normally be of no consequence. Alternatively, VDRV+ can be supplied independently from a higher

voltage supply.

2. The capacitor is charged negatively whenever RXIN is in a marking (or idle) state. When the DS276 is

transmitting marking data and RXIN is spacing the capacitor will discharge towards ground with a

time constant determined by the capacitor value and the value of the load resistance. The value shown

should store sufficient charge for reliable operation up to 20 kbps.

3. RXIN must never be allowed to reach a negative voltage with respect to VDRV- or excessive currents

will be drawn. Therefore, if negative voltage swings are present on RXIN, VDRV- should not be

connected to ground and the circuit shown in Figure 4 should be used.

DS276 Datasheet(PDF) 5 Page - Dallas Semiconductor