DS8935 Datasheet, PDF (8/12 Pages) National Semiconductor (TI) – LocalTalk™ Dual Driver/Triple Receiver

Typical Application Information (Continued)
TABLE 1. Device Pin Descriptions
Pin#
2, 4
3
Name
D_IN
D_EN1
19
17, 18
13, 15
16, 14
5, 6, 7
9
12
10, 11
8
1
20
D_OUT+
D_OUT−
R_IN+
R_IN−
R_OUT
R_EN
R_EN
N/C
GND
V_EE
V_CC
Description
TTL Driver Input Pins
Active Low Driver Enable Pin. A High on this Pin TRI-STATEs the Driver
Outputs (D1 Only)
Non-Inverting Driver Output Pin
Inverting Driver Output Pin
Non-Inverting Receiver Input Pin
Inverting Receiver Input Pin
Receiver Output Pin
Active Low Receiver Enable
Active High Receiver Enable
Not Connected
Ground Pin
Negative Power Supply Pin, −5V ±5%
Positive Power Supply Pin, +5V ±5%
DRIVER OUTPUT WAVEFORMS
The driver configuration on the DS8935 is unique among
TIA/EIA-422 devices in that it utilizes −5V V_EE supply. A typi-
cal TIA/EIA-422 driver uses +5V only and generates signal
swings of approximately 0V–5V.
By utilizing V_EE, the differential driver is able to generate a
much larger differential signal. The typical output voltage is
about |4| V, which gives |8| V differentially, thus providing a
much greater noise margin than +5V drivers. See Figure 13.
The receiver therefore has a range of +8V to −8V or V_SS of
16V (V_SS = V_OD–V_OD*).
Each side of the differential driver operates similar to a TIA/
EIA-423 driver. The output voltages are slightly different due
to the loading: the differential driver has differential termina-
tion, the single-ended driver is terminated with a resistor to
ground.
Note 9: V_CC = +5V, V_EE = −5V
Note 10: D1 Enabled (Active)
DS012066-15
FIGURE 13. Typical Driver Output Waveforms
DS012066-16
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