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Texas Instruments SN74ALS29854NT3
- Part No.:
- SN74ALS29854NT3
- Manufacturer:
- Texas Instruments
- Package:
- 24-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74ALS29854NT3.pdf
- Description:
- IC TXRX INVERT 5.25V 24DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
SN74ALS29854NT3 from Texas Instruments is an 8-bit to 9-bit parity bus transceiver with integrated parity generator/checker, open-collector ERR flag, latch-enable (LE) and clear (CLR) controls, and dual-directional A↔B data transfer. It operates at 5 V (4.75–5.25 V), supports 0°C to 70°C ambient, and delivers 8 ns propagation delay (A/B ↔ B/A, CL = 50 pF). It is used in legacy industrial backplane systems requiring real-time parity error detection and flag storage.
For engineers reviewing the SN74ALS29854NT3 datasheet, SN74ALS29854NT3 pinout, SN74ALS29854NT3 application, or SN74ALS29854NT3 equivalent, key selection criteria include open-collector ERR output drive capability (IOL = 48 mA), inverted-parity diagnostic mode, latch-controlled error flag retention, and NT-package DIP-24 mechanical compatibility with legacy board layouts.
Technical Context
The SN74ALS29854NT3 implements a dual-mode 8→9-bit parity transceiver: in A→B direction it generates odd parity across A1–A8 plus PARITY output; in B→A direction it checks incoming B1–B8 + PARITY against odd parity and asserts ERR low on mismatch. The ERR flag is edge-sensitive-latched on LE high, cleared on CLR low, and passed transparently when LE low and CLR high.
Its control logic supports four functional states: bidirectional isolation (OEA=OEB=high), A→B transfer with parity generation (OEA=low, OEB=high), B→A transfer with parity checking (OEA=high, OEB=low), and A→B transfer with forced inverted parity (OEA=OEB=low). All I/Os are TTL-compatible with VIH = 2 V, VIL = 0.8 V, and VOH ≥ 2.4 V (IOH = –24 mA).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.75 V to 5.25 V - ensures stable operation under standard 5 V TTL rail tolerances |
| Propagation Delay (A↔B) | 8 ns (CL = 50 pF) - enables ≤125 MHz bus timing in short-trace backplane designs |
| ERR Output Drive | IOL = 48 mA - supports direct connection to LED indicators or TTL-input latches without buffering |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade industrial control cabinets and test equipment |
| Input Thresholds | VIH = 2.0 V, VIL = 0.8 V - guarantees interoperability with standard ALS/TTL logic families |
| Parity Mode | Odd parity generation and checking - matches industry-standard memory and bus integrity protocols |
| Output Enable Logic | OEA/OEB active-low - allows independent gating of A-side and B-side drivers for flexible bus arbitration |
Pinout & Package
SN74ALS29854NT3 uses a 300-mil plastic dual-in-line package (PDIP-24, NT suffix), with 2.54 mm pitch, 7.62 mm body width, and through-hole mounting. Pin 1 is top-left corner (notch-up orientation).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OEA) | A-side output enable | Active-low control enabling/disabling A1–A8 drivers; high = high-impedance A outputs |
| 2–9 (A1–A8) | A-bus data inputs/outputs | Bidirectional I/O ports for 8-bit source/sink; driven when OEA low, high-Z when OEA high |
| 10 (ERR) | Open-collector parity error flag | Low-active output indicating B-bus parity mismatch; requires external pull-up for logic-level interface |
| 11 (CLR) | Error-flag clear input | Active-low asynchronous reset of internal ERR latch; forces ERR high regardless of parity state |
| 12 (GND) | Ground reference | Primary return path for all digital and output current; must be low-inductance connection |
| 13 (VCC) | Power supply | +5 V supply pin; bypassing with 0.1 µF ceramic capacitor near pin is mandatory for noise immunity |
| 14 (B1) | B-bus data inputs/outputs | First of eight bidirectional I/O ports for B-bus; driven when OEB low, high-Z when OEB high |
| 15–22 (B2–B8) | B-bus data inputs/outputs | Remaining B-bus I/O lines; functionally identical to B1 with shared OEB control |
| 23 (PARITY) | 9th-bit parity I/O | Provides generated odd parity during A→B transfer; serves as parity input during B→A checking |
| 24 (OEB) | B-side output enable | Active-low control enabling/disabling B1–B8 drivers; high = high-impedance B outputs |
| LE (Pin 16) | Latch-enable control | High level captures and holds current ERR state in internal register; low level passes ERR transparently |
Key Features
| Feature | Design Value |
|---|---|
| Integrated parity generator/checker | Eliminates need for external XOR networks or discrete parity ICs in 8-bit data paths |
| Open-collector ERR output | Allows wired-OR connection of multiple SN74ALS29854NT3 devices to a single system error bus |
| Latched error-flag register | Enables non-volatile capture of transient parity errors for post-fault diagnostics without continuous polling |
| Inverted-parity diagnostic mode | Forces ERR assertion during A→B transfer (OEA=OEB=low) to verify downstream error-handling logic |
| TTL-compatible input/output levels | Direct drop-in replacement for legacy 74ALS/74AS logic without level-shifting circuitry |
Applications
| Industrial Backplane Data Transfer | Legacy Memory Subsystem Integrity |
|---|---|
Use Scenario: Bidirectional data exchange between CPU and peripheral cards across a 24-pin ISA-style backplane with parity monitoring. IC Role / Device Role / Timing Role: SN74ALS29854NT3 acts as the parity-aware bus transceiver, generating odd parity on write cycles and validating it on read cycles while asserting ERR on mismatch. Use Value: Enables real-time detection of bit corruption caused by crosstalk, connector wear, or EMI in long-run parallel buses. | Use Scenario: Parity checking of 8-bit data reads from static RAM modules in embedded controllers built before 1995. IC Role / Device Role / Timing Role: SN74ALS29854NT3 interfaces RAM data bus to CPU, providing hardware-level parity validation synchronized to memory access strobes. Use Value: Reduces firmware overhead by offloading parity computation and error signaling to dedicated logic, improving deterministic response time. |
| Test Equipment Self-Diagnostic Bus | Programmable Logic Controller I/O Expansion |
Use Scenario: Internal diagnostic bus in automated test equipment where each module reports status via parity-encoded handshake signals. IC Role / Device Role / Timing Role: SN74ALS29854NT3 provides isolated, parity-checked communication between main controller and daughterboard sensors/actuators. Use Value: Supports fault-isolation by latching ERR state (via LE) during power-on self-test, allowing root-cause identification without host intervention. | Use Scenario: Adding parity-protected I/O expansion to legacy PLC racks using parallel bus architecture. IC Role / Device Role / Timing Role: SN74ALS29854NT3 buffers and validates data between CPU bus and remote I/O modules, with ERR tied to PLC fault LED driver. Use Value: Extends mean time between failures (MTBF) by catching wiring faults or module misinsertion before process disruption occurs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parity transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AS29854N | Faster propagation delay (5 ns vs. 8 ns), higher ICC (120 mA), AS-family speed grade; same pinout and logic function | Better suited for high-speed backplanes (>20 MHz) but requires tighter power delivery and thermal management | Select SN74AS29854N only if timing margin is insufficient with SN74ALS29854NT3 and board layout supports AS-family noise requirements |
| AM29854PC | Functionally identical per AMD datasheet SD-29854-1; same pinout, timing, and electrical specs; manufactured by Advanced Micro Devices | No change in system integration; validated in same-era military and telecom designs as second-source option | AM29854PC is a direct second-source alternative with identical form, fit, and function-ideal for supply chain diversification in legacy production |
Compared with SN74ALS29854NT3, SN74AS29854N offers higher speed at increased power and noise sensitivity, while AM29854PC provides identical performance with alternate sourcing-making the latter preferred for continuity in existing designs.
Availability
SN74ALS29854NT3 is available at Aetrix Electronics and suitable for industrial backplane data transfer, legacy memory subsystem integrity, test equipment self-diagnostic bus, and programmable logic controller I/O expansion requiring stable component supply and long-term obsolescence support.
Supply support for SN74ALS29854NT3 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial and automotive reach.
The SN74ALS29854NT3 belongs to TI's 74ALS advanced low-power Schottky logic family, designed specifically for high-reliability, medium-speed parallel bus applications in commercial-temperature industrial systems.
FAQ
What is the operating temperature range for the SN74ALS29854NT3?
The SN74ALS29854NT3 is characterized for operation from 0°C to 70°C, meeting commercial-grade specifications. This range supports deployment in controlled-environment industrial cabinets, benchtop test equipment, and non-automotive embedded systems. Operation outside this range may result in undefined timing behavior or increased error rates, and is not guaranteed by Texas Instruments' datasheet SDAS118C.
Does the SN74ALS29854NT3 support both even and odd parity modes?
No-the SN74ALS29854NT3 implements odd parity exclusively, as confirmed by its functional description, truth table, and logic diagram. It generates odd parity across A1–A8 and checks incoming B1–B8 + PARITY against odd parity. There is no provision for even-parity configuration; the "inverted parity" mode (OEA=OEB=low) forces an intentional error condition-not a parity mode switch.
How does the ERR output behave when OEA and OEB are both high?
When both OEA and OEB are high, the SN74ALS29854NT3 enters isolation mode: all A1–A8 and B1–B8 I/Os go high-impedance, and ERR reflects inverted parity of the A bus (per datasheet footnote §). In this state, ERR is active and indicates A-bus parity status-not B-bus-and remains controllable via LE/CLR. This behavior enables passive monitoring of A-side data integrity without bus loading.
Can the SN74ALS29854NT3 be used with modern 3.3 V systems?
No-the SN74ALS29854NT3 is a 5 V-only device with absolute maximum VCC of 7 V and recommended VCC of 4.75–5.25 V. Its input thresholds (VIH = 2.0 V, VIL = 0.8 V) and output drive (VOH ≥ 2.4 V at –24 mA) are incompatible with 3.3 V logic families without level translation. Direct connection risks undriven inputs, marginal noise margins, or excessive current draw; use of a voltage translator or replacement with a 3.3 V–compatible parity IC is required.
Is the SN74ALS29854NT3 RoHS-compliant?
No-the SN74ALS29854NT3 is marked "OBSOLETE" by Texas Instruments with no defined Pb-Free or RoHS conversion plan (Eco Plan = TBD). Its NT-package construction predates RoHS requirements, and TI documentation confirms lead-based solder and terminations. For new designs requiring RoHS compliance, consider redesign with modern alternatives or verified lead-free legacy sources subject to full chemical analysis.
SN74ALS29854NT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 24-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- Transceiver, Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 24mA, 48mA
- Voltage - Supply:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 24-PDIP
SN74ALS29854NT3 FAQ
1.How can I place an order for SN74ALS29854NT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS29854NT3 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
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The price and inventory of SN74ALS29854NT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS29854NT3 is usually 5 days.
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SN74ALS29854NT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS29854NT3 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SN74ALS29854NT3?
For technical support, including SN74ALS29854NT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS29854NT3 requirements.
6.How does Aetrix verify that SN74ALS29854NT3 is sourced from the original manufacturer or authorized distributors?
All SN74ALS29854NT3 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74ALS29854NT3 meets industry standards.
7.What is the process for return or replacement of SN74ALS29854NT3?
All SN74ALS29854NT3 units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS29854NT3, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SN74ALS29854NT3 part is unused and in its original packaging.
Return procedure for SN74ALS29854NT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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