DS8925 datasheet(9/16 Pages) NSC

9 / 16 page

Typical Application Information (Continued)

SINGLE +5V SUPPLY

The DS8925 is derived from the DS3691/92 which could be

configured using a single +5V supply (V

EE = 0V). This device

is not specified for this type of operation. However, the de-

vice will not be damaged if operated using a single +5V sup-

ply.

Both drivers require the −5V supply in order to meet the out-

put voltage levels specified. When the device switches from

a positive voltage to the complimentary state, it is pulled to-

ward the V

EE level. If that level is 0V, then the complimentary

state will be near 0V instead of V

EE. Thus, the output would

switch from about 4V to 0V, instead of 4V to −4V. The differ-

ential driver will meet TIA/EIA-422, but with a reduced noise

margin. The single-ended driver will not meet TIA/EIA-423

without the −5V supply.

The receivers will be functional but may suffer parametri-

cally. The inverting receiver is referenced to V

EE therefore,

the threshold may shift slightly. The inputs can still vary over

the ±10V common mode range.

Typical Performance Characteristics (Note 10)

DS011895-16

Note 9: Star (*) represents the opposite input condition for a parameter.

FIGURE 13. Differential Communication, Transformer-Coupled to a Twisted-Pair Line

Differential Driver Output

Voltage vs Output Current

DS011895-17

Differential Driver Output

Voltage vs Output Current

DS011895-18

DS8925 Datasheet(PDF) 9 Page - National Semiconductor (TI)