Designed for Digital Data Transmission

Over 50-W to 500-W Coaxial Cable, Strip

Line, or Twisted Pair

High Speed

tpd = 20 ns Maximum at CL = 15 pF

TTL Compatible With Single 5-V Supply

2.4-V Output at IOH = –75 mA

Uncommitted Emitter-Follower Output

Structure for Party-Line Operation

Short-Circuit Protection

AND-OR Logic Configuration

Designed for Use With Triple Line

Receivers SN55122, SN75122

Designed to Be Interchangeable With

Signetics N8T13

description

The SN55121 and SN75121 dual line drivers are

designed for digital data transmission over lines

having impedances from 50 to 500 W. They are

also compatible with standard TTL logic and

supply-voltage levels.

The low-impedance emitter-follower outputs of

the SN55121 and SN75121 can drive terminated

lines such as coaxial cable or twisted pair. Having

the outputs uncommitted allows wired-OR logic to

be performed in party-line applications. Output

short-circuit protection is provided by an internal

clamping network that turns on when the output

voltage drops below approximately 1.5 V. All of the

inputs are in conventional TTL configuration and

the gating can be used during power-up and

power-down sequences to ensure that no noise is

introduced to the line.

The SN55121 is characterized for operation over

the full military temperature range of –55°C to

125°C. The SN75121 is characterized for

operation from 0°C to 70°C.