SN75123D - Dual TTL Line Driver | Texas Instruments
MPN: SN75123D ✓ פעילSN75123D סקירה
A line driver is a digital interface IC that converts logic-level inputs into stronger output signals capable of driving terminated cables, coaxial links, or twisted-pair lines. The dual SN75123 belongs to the line-driver and receiver class of interface ICs. Its primary role is to improve signal integrity and drive capability across long or shared bus wiring rather than to perform data conversion or voltage regulation.
The SN75123D operates from one 5 V supply and is compatible with standard-TTL logic levels. Its emitter-follower outputs are designed for low-impedance line driving and support party-line operation, where multiple drivers can share a bus when their outputs are appropriately controlled. The output structure also provides short-circuit protection, a useful characteristic when a connected line is faulted or incorrectly terminated.
The 3.11 V output level at -59.3 mA indicates strong high-level output drive capability. With a maximum transmit delay of 25 ns, the device supports communication systems that require faster edge propagation than general-purpose logic buffers. The manufacturer identifies the SN75123 family as meeting or exceeding the IBM System 360 input/output interface requirements while remaining compatible with standard-TTL supply and logic levels.
Typical uses include terminated coaxial cable links, twisted-pair communication channels, computer peripheral interfaces, industrial data links, and legacy equipment built around TTL or IBM System 360 interfaces. Because the outputs use an uncommitted emitter-follower structure, designers can implement party-line networks in which connected drivers share the same physical conductor.
For a new design, verify the receiver's threshold requirements, line termination, cable length, and grounding arrangement before assigning the driver. The 16-pin SOIC package simplifies assembly and rework, but the output enable, input, ground, and supply pins must be connected according to the manufacturer datasheet. A single 5 V rail and common ground reference are fundamental to reliable operation.
This product page combines the manufacturer's functional description with engineering-focused comparison, application, and design guidance. It also clearly distinguishes directly substitutable components from candidates that require different packages or interfaces, helping engineers preserve PCB compatibility when planning replacements or design reuse.
חלופות תחליף ישיר עבור SN75123D — אותו מארז, תואם פין-לפין. חלקים במארז שונה הדורשים עיבוד מחדש של ה-PCB אינם נכללים.
אין חלופות תואמות Drop-in עבור מוצר זה.
בקשת חלופותSN75123D מפרטים
| Product Type | Dual line driver |
| Number of Drivers | 2 channels |
| מתח אספקה | 5 V |
| Maximum Supply Voltage | 5.25 V |
| Logic Compatibility | Standard TTL |
| Interface Standard | IBM System 360 input/output interface |
| מתח פלט | 3.11 V at -59.3 mA |
| Maximum Transmit Delay | 25 ns |
| Maximum Supply Current | 60 mA |
| Output Structure | Uncommitted emitter-follower |
| Party-Line Operation | Supported |
| Short-Circuit Protection | Yes |
| מארז | 16-pin SOIC |
| סוג הרכבה | Surface mount |
| Terminal Count | 16 terminals |
מדריך תצורת פינים של SN75123D 16-pin soic
תצורת פינים עבור SN75123D (מארזת 16-pin soic). מספרי פינים, פונקציות ותרשימי חיבורים מוגדרים ב-Datasheet של היצרן. יש לעיין בו לקבלת ה-footprint המדויק והנחיות הלחמה.
אין נתוני פריסת פינים מפורטים עבור SN75123D.
עיינו ב- גיליון נתונים עבור תצורת פינים מלאה.
יישומים טיפוסיים
SN75123D מתאים עבור 6 יישוםs: Terminated Coaxial Data Links, Twisted-Pair Communication Channels, IBM System 360 Legacy Interfaces, Party-Line Peripheral Buses, Industrial Data Acquisition, Test and Measurement Interfaces.
Terminated Coaxial Data Links
The SN75123D is appropriate for terminated coaxial data links because its dual emitter-follower outputs provide low-impedance drive for cable-connected receivers. The manufacturer specifies a 3.11 V output at -59.3 mA and a maximum transmit delay of 25 ns, allowing the device to retain useful signal strength and timing performance across a designed line. The transmitter operates from one 5 V supply and is compatible with standard-TTL inputs. In implementation, the cable characteristic impedance, receiver input loading, shield connection, and source termination should be evaluated together because the device does not create an appropriate termination by itself.
מומלץ
Twisted-Pair Communication Channels
The SN75123D can drive twisted-pair communication channels where the system requires a single-ended TTL-compatible interface and stronger source drive than standard logic provides. Its low-impedance emitter-follower outputs are specifically described for terminated lines, while short-circuit protection helps contain fault conditions on an externally routed conductor. With a maximum transmit delay of 25 ns, the device is suitable for moderate-speed communication links. PCB implementation should provide a continuous return path, proper line termination, and clean separation between the two driver channels to limit crosstalk.
מומלץ
IBM System 360 Legacy Interfaces
The SN75123D was designed specifically for IBM System 360 input/output interface requirements and is therefore relevant to equipment that retains this legacy electrical interface. It operates from a single 5 V supply, accepts standard-TTL-compatible signals, and provides two independent line-driver channels for terminated conductors. The 3.11 V output at -59.3 mA supports the stronger signaling expected by this interface class. When modernizing legacy equipment, preserve the original termination and receiver arrangement unless a complete signal-integrity review establishes that the interface can be adapted safely.
מומלץ
Party-Line Peripheral Buses
The SN75123D fits party-line peripheral buses because its uncommitted emitter-follower outputs allow multiple connected drivers to share one conductor when their enables are sequenced correctly. This architecture suits legacy backplane and peripheral arrangements in which every attached transmitter can be placed in a high-impedance state. Short-circuit protection improves robustness when a connected line is faulted. Timing must still prevent two enabled drivers from driving the bus in opposite states, and the system designer should validate contention behavior, receiver thresholds, and cable fall time before production use.
מומלץ
Industrial Data Acquisition
The SN75123D can serve as the line transmitter in industrial data-acquisition equipment that uses a legacy 5 V TTL-compatible cable interface. Its two channels reduce the component count for dual-line links, while the stated 25 ns maximum transmit delay supports communication at speeds substantially above slow asynchronous control rates. The emitter-follower output and short-circuit protection are useful in externally connected equipment. Industrial qualification still depends on the complete system's temperature requirements, surge protection, isolation strategy, and regulatory compliance rather than the line-driver IC alone.
מומלץ
Test and Measurement Interfaces
The SN75123D is useful in test and measurement equipment that must stimulate remote receivers over terminated cable runs. Its low-impedance emitter-follower outputs provide stronger drive than conventional logic buffers, while the 3.11 V output at -59.3 mA specification supports a defined high-level load. The maximum transmit delay of 25 ns provides useful timing margin for moderate-speed control or measurement buses. Instrument designers should account for cable attenuation, connector reflections, receiver loading, and the difference between logical command speed and the rise time of the physical transmission line.
מומלץ
סיכום מוצרים מומלצים
נתוני עזר הנדסיים עבור SN75123D — השוואה, הנחיות תכנון ומידע על תאימות.
מדריך בחירה
השוואה עם חלופות
| פרמטר | מוצר זה |
|---|---|
| Product Type | Dual line driver |
| Number of Channels | 2 |
| Supply Voltage | 5 V |
| Maximum Supply Voltage | 5.25 V |
| Output Voltage | 3.11 V at -59.3 mA |
| Maximum Transmit Delay | 25 ns |
| Maximum Supply Current | 60 mA |
| Logic Compatibility | Standard TTL |
| Output Structure | Uncommitted emitter-follower |
| Package | 16-pin SOIC |
| Brand | Texas Instruments |
הערות תכנון
Do not enable two SN75123D outputs simultaneously when they connect to the same party-line conductor with opposite output states. The uncommitted emitter-follower architecture permits shared-bus use only when output-enable sequencing keeps inactive drivers at high impedance. Review every connected driver and receiver in the complete bus, not just the local transmitter.
Treat the external line as a transmission-line problem when distance, data rate, or connector transitions are significant. Characteristic-impedance matching, source or load termination, stub length, and connector reflections determine whether the 3.11 V output at -59.3 mA and 25 ns maximum transmit delay produce a usable receiver waveform. Validate the assembled cable and termination network with suitable measurement equipment.
Route each driver output directly toward its connector or termination network, and keep the return-current path continuous beneath or adjacent to the signal trace. Place local supply bypassing at the device and maintain a low-impedance ground reference. Separate the two line-driver channels when they carry unrelated or high-slew-rate signals to minimize crosstalk.
Design the 5 V rail for the stated 60 mA maximum supply current plus the load presented by the receiving interface and associated circuitry. Decoupling should follow the manufacturer datasheet recommendations, and the supply must remain within the 5.25 V maximum. Verify startup and fault behavior at the board level rather than assuming the nominal 5 V rail is always sufficient.
מידע על תאימות
No explicit compliance declarations are identified in the manufacturer product-page summary or distributor results. Confirm RoHS, REACH, lead-free, halogen-free, and conflict-minerals status from the current manufacturer documentation or applicable material declarations before procurement.