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Texas Instruments SN74ALS29854DW
- Part No.:
- SN74ALS29854DW
- Manufacturer:
- Texas Instruments
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS29854DW.pdf
- Description:
- IC TXRX INVERT 5.25V 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,835
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Product details
Overview
SN74ALS29854DW from Texas Instruments is an 8-bit to 9-bit parity bus transceiver with integrated odd-parity generation and checking, open-collector ERR flag output, latch-enable (LE) and clear (CLR) control, and dual-directional A↔B data transfer capability. 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), enabling high-speed system-level parity validation in backplane or memory bus architectures.
For engineers reviewing the SN74ALS29854DW datasheet, SN74ALS29854DW pinout, SN74ALS29854DW application, or SN74ALS29854DW equivalent, key selection criteria include its bidirectional parity-aware bus isolation, ERR flag latching behavior, inverted-parity diagnostic mode, and SOIC-24 package compatibility with legacy TTL/ALS logic families.
Technical Context
The SN74ALS29854DW implements a synchronous 9-bit parity generator/checker with dedicated PARITY output and open-collector ERR flag that reflects real-time parity mismatch on B-bus + PARITY input. Its internal logic enables three distinct operational modes: A→B parity generation (odd or inverted), B→A parity checking, and ERR flag storage/clearing via LE and CLR control inputs.
It uses ALS (Advanced Low-Power Schottky) bipolar technology, ensuring TTL-compatible voltage thresholds (VIH = 2 V, VIL = 0.8 V), 24 mA sink capability on ERR, and 48 mA IOL drive on I/O ports. The device supports 3-state outputs controlled independently by OEA and OEB, allowing full bus isolation when both are high.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.75 V to 5.25 V - ensures stable operation within standard 5 V TTL/ALS rail tolerances. |
| Propagation Delay | 8 ns (A/B ↔ B/A, CL = 50 pF) - enables ≤125 MHz bus cycle timing in parity-checked systems. |
| Parity Function | Odd-parity generation and checking - detects single-bit errors on 8-bit data + 1 parity bit. |
| ERR Output Type | Open-collector - allows wired-OR fault signaling across multiple transceivers on shared error bus. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded and industrial control applications. |
| I/O Drive Strength | 48 mA sink (IOL), –24 mA source (IOH) - drives standard TTL loads without external buffers. |
| Package | SOIC-24 (DW) - surface-mount footprint compatible with automated PCB assembly and thermal management. |
Pinout & Package
SN74ALS29854DW is housed in a 24-pin plastic small-outline integrated circuit (SOIC) package per JEDEC MS-013, with 300-mil body width, 1.27 mm lead pitch, and RoHS-compliant CU-NiPdAu finish (Level-2 moisture sensitivity).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OEA) | A-side output enable | Active-low control enabling A1–A8 drivers; high = high-impedance A-bus output. |
| 2–9 (A1–A8) | A-bus data inputs/outputs | Bidirectional 8-bit port; direction determined by OEA/OEB states and data flow mode. |
| 10 (ERR) | Parity error flag | Open-collector output asserting low on B-bus parity mismatch; requires external pull-up. |
| 11 (CLR) | Error-flag clear | Active-low asynchronous reset of internal ERR latch; clears stored error state immediately. |
| 12 (GND) | Ground reference | Primary return path for all digital and I/O currents; must be low-impedance connection. |
| 13 (VCC) | Power supply | +5 V supply input; decoupling capacitor required near pin for noise suppression. |
| 14–21 (B1–B8) | B-bus data inputs/outputs | Bidirectional 8-bit port; receives A→B data or supplies B→A data with parity check. |
| 22 (PARITY) | Generated parity bit | 9th output during A→B transfer; carries odd-parity value for A1–A8 or forced-inverted parity. |
| 23 (OEB) | B-side output enable | Active-low control enabling B1–B8 drivers; high = high-impedance B-bus output. |
| 24 (LE) | Latch-enable | Active-high edge-triggered strobe capturing current ERR state into internal register. |
Key Features
| Feature | Design Value |
|---|---|
| Inverted-parity diagnostic mode | When OEA=OEB=L, forces parity error to expose system-level fault injection paths and verify ERR handling. |
| ERR flag latching and clearing | LE and CLR provide deterministic capture and reset of transient parity errors for debug and logging. |
| Dual independent 3-state controls | OEA and OEB allow asymmetric bus isolation-e.g., A-bus active while B-bus tri-stated-enabling flexible arbitration. |
| ALS bipolar process | Delivers TTL-compatible speed/power trade-off: 8 ns delay with 100 mA max ICC, lower than standard LS. |
| Open-collector ERR with 24 mA sink | Supports multi-drop error bus wiring without level shifters; compatible with 5 V pull-up networks. |
Applications
| Backplane Data Integrity | Memory Subsystem Parity |
|---|---|
|
Use Scenario: Bidirectional data routing between CPU and peripheral cards across a passive backplane with shared parity bus. IC Role / Device Role / Timing Role: SN74ALS29854DW acts as parity-aware transceiver on each slot, generating parity on outbound writes and checking parity on inbound reads. Use Value: Detects single-bit corruption during hot-swap or long-trace transmission, reducing uncorrectable memory errors by validating parity before data acceptance. |
Use Scenario: Interfacing 8-bit wide DRAM modules with parity support in industrial controllers requiring ECC-adjacent reliability. IC Role / Device Role / Timing Role: SN74ALS29854DW sits between memory controller and DRAM data bus, inserting parity on write cycles and verifying it on read cycles. Use Value: Enables cost-effective parity protection without full ECC silicon, leveraging existing ALS logic infrastructure and 8 ns timing margin. |
| Legacy System Bus Extension | Diagnostic Test Equipment Interface |
|
Use Scenario: Extending aging 8-bit ISA or STD bus systems with parity-aware expansion slots for field-serviceable modules. IC Role / Device Role / Timing Role: SN74ALS29854DW provides pin-compatible parity augmentation to original bus transceivers, retaining timing and voltage compatibility. Use Value: Adds field-proven parity checking to legacy designs without redesigning bus controllers or altering clock domains. |
Use Scenario: Built-in self-test (BIST) subsystem in automated test equipment where parity faults must be captured and logged across multiple test cycles. IC Role / Device Role / Timing Role: SN74ALS29854DW's LE/CLR-controlled ERR latch stores intermittent parity failures between test sequences for post-analysis. Use Value: Eliminates need for external flip-flops or microcontroller polling, reducing test head component count and firmware complexity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8-bit parity transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AS29854DW | Faster propagation delay (5 ns vs. 8 ns), higher ICC (120 mA), AS-series TTL threshold (VIH = 2.0 V same, but VIH min tighter at 2.0 V). | Requires stricter VCC regulation and higher power budget; better suited for high-frequency bus clocks >150 MHz. | Select SN74AS29854DW only if timing closure demands sub-6 ns delay and system can accommodate increased power dissipation. |
| AM29854PC | Functionally identical per AMD datasheet, same pinout and logic, but PDIP-24 (PC) package and wider temp range (–55°C to +125°C). | Used in military/aerospace applications requiring extended temperature operation and through-hole assembly. | Choose AM29854PC when extended temperature compliance or through-hole mounting is mandatory; otherwise SN74ALS29854DW offers superior surface-mount manufacturability. |
Compared with SN74AS29854DW and AM29854PC, the SN74ALS29854DW balances commercial-temperature performance, low-power ALS efficiency, and SOIC-24 packaging-making it optimal for cost-sensitive, high-volume industrial backplanes where 8 ns timing suffices and RoHS compliance is required.
Availability
SN74ALS29854DW is available at Aetrix Electronics and suitable for backplane interconnects, memory subsystems, legacy bus extensions, and diagnostic test interfaces requiring stable component supply and long-term industrial availability.
Supply support for SN74ALS29854DW 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 global semiconductor leader specializing in analog, embedded processing, and logic solutions, with decades of heritage in TTL, ALS, and advanced logic families.
The SN74ALS29854DW belongs to TI's legacy ALS logic portfolio, engineered specifically for high-reliability, parity-critical bus interfacing in commercial industrial systems where speed, noise immunity, and backward compatibility are essential.
FAQ
What is the primary function of the SN74ALS29854DW in a data bus architecture?
The SN74ALS29854DW serves as an 8-bit to 9-bit parity bus transceiver that generates odd parity during A→B transfers and checks parity during B→A transfers. Its ERR output flags mismatches, while LE and CLR allow latching and clearing of error states-enabling robust data integrity monitoring in bidirectional bus systems without external logic.
How does the inverted-parity mode work on the SN74ALS29854DW?
When both OEA and OEB are low, the SN74ALS29854DW enters inverted-parity mode: it generates a deliberate parity error on the PARITY output during A→B transfer. This forces the ERR line low, providing a hardware-level diagnostic stimulus to verify downstream error-handling circuitry and software response without requiring corrupted data injection.
Can the SN74ALS29854DW operate with modern 3.3 V systems?
No-the SN74ALS29854DW is strictly a 5 V device with TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) and absolute maximum ratings up to 7 V. It lacks 3.3 V tolerance and will not interface reliably with 3.3 V logic without level translation; it is intended for legacy 5 V ALS/TTL environments.
What is the purpose of the open-collector ERR output on the SN74ALS29854DW?
The open-collector ERR output on the SN74ALS29854DW enables wired-OR connection of multiple transceivers onto a shared error bus. Any device detecting a parity mismatch pulls ERR low, allowing centralized fault detection. An external pull-up resistor (typically 4.7 kΩ to 5 V) is required to establish the high state when no error is present.
Is the SN74ALS29854DW pin-compatible with the AM29854 series?
Yes-the SN74ALS29854DW is functionally and pin-compatible with AMD's AM29854 in matching packages (e.g., DW SOIC-24). Both share identical pin assignments, logic behavior, and timing specifications, making them direct drop-in alternatives in commercial-temperature applications where ALS speed/power characteristics are acceptable.
SN74ALS29854DW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
SN74ALS29854DW FAQ
1.How can I place an order for SN74ALS29854DW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS29854DW on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SN74ALS29854DW reliable?
The price and inventory of SN74ALS29854DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS29854DW is usually 5 days.
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SN74ALS29854DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS29854DW 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 SN74ALS29854DW?
For technical support, including SN74ALS29854DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS29854DW requirements.
6.How does Aetrix verify that SN74ALS29854DW is sourced from the original manufacturer or authorized distributors?
All SN74ALS29854DW 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 SN74ALS29854DW meets industry standards.
7.What is the process for return or replacement of SN74ALS29854DW?
All SN74ALS29854DW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS29854DW, 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 SN74ALS29854DW part is unused and in its original packaging.
Return procedure for SN74ALS29854DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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