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Texas Instruments SN74BCT29861BNT
- Part No.:
- SN74BCT29861BNT
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
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SN74BCT29861BNT.pdf
- Description:
- BUS TRANSCEIVER
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Product details
Overview
SN74BCT29861BNT from Texas Instruments is a 10-bit BiCMOS bus transceiver enabling bidirectional asynchronous data transfer between A and B buses, with dual output-enable controls (OEAB/OEBA), 5-V supply operation, ±24 mA high-level/48 mA low-level drive capability, and power-up high-impedance state for hot-insertion safety in backplane and motherboard interconnects.
For engineers reviewing the SN74BCT29861BNT datasheet, SN74BCT29861BNT pinout, SN74BCT29861BNT application, or SN74BCT29861BNT equivalent, key selection criteria include direction control logic mapping, bus isolation timing (tPZH/tPHZ ≤ 8.1 ns), standby current (ICC ≤ 12 mA when disabled), and compatibility with TTL/LS logic families in legacy industrial control and telecom line-card designs.
Technical Context
This device implements dual independent enable logic: OEAB = L and OEBA = H enables A→B transmission; OEAB = H and OEBA = L enables B→A transmission; both high isolates buses; both low latches A = B. Its BiCMOS process delivers TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2 V) while reducing ICC(off) to 6.5–12 mA versus bipolar-only equivalents.
Switching performance is specified under 50-pF load and 500-Ω source impedance, with propagation delays tPLH/tPHL ≤ 6.8 ns and output-enable-to-output transitions (tPZH/tPLZ/tPHZ/tPZL) ranging from 5.0 to 11.7 ns - optimized for synchronous bus handshaking without external clock alignment.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - supports standard 5-V TTL systems with ±10% tolerance |
| Output Drive | −24 mA (IOH), +48 mA (IOL) - drives 20+ TTL loads or stub-loaded backplane traces |
| Propagation Delay | ≤6.8 ns (tPHL, VCC = 4.5 V, CL = 50 pF) - enables >100-MHz bus toggle rates in point-to-point links |
| Enable Transition Time | tPZH ≤ 8.1 ns - ensures clean bus isolation during direction switching without glitches |
| Input Thresholds | VIH = 2.0 V, VIL = 0.8 V - fully compatible with 74ALS/74AS and earlier TTL families |
| Power-Up State | Outputs high-impedance - prevents bus contention during system reset or hot-swap initialization |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded control and telecom infrastructure |
Pinout & Package
SN74BCT29861BNT uses a 300-mil plastic DIP (NT package) with 24 leads. Pin 1 is OEBA, pin 2 is A1, continuing sequentially to pin 11 (A10), pin 12 is GND, pin 13 is VCC, pin 14 is B10, then B9 through B1 on pins 15–23, and pin 24 is OEAB.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OEBA (Pin 1) | Output Enable A→B | Active-low control: asserts A→B path when low; high-impedance otherwise |
| A1–A10 (Pins 2–11) | Input/Output Port A | Bidirectional I/O pins for first bus segment; driven by B when OEBA = L & OEAB = H |
| GND (Pin 12) | Ground Reference | Primary signal return for all I/O and internal logic; decoupling required at VCC pin |
| VCC (Pin 13) | Supply Voltage | +5 V power rail; must be bypassed with ≥0.1 µF ceramic capacitor near pin |
| B1–B10 (Pins 14–23) | Input/Output Port B | Bidirectional I/O pins for second bus segment; driven by A when OEAB = L & OEBA = H |
| OEAB (Pin 24) | Output Enable B→A | Active-low control: asserts B→A path when low; high-impedance otherwise |
Key Features
| Feature | Design Value |
|---|---|
| BiCMOS Process | Reduces standby ICC to 6.5–12 mA vs. 30–50 mA in bipolar 74ALS29861 - cuts board-level power by ~40% |
| Dual Independent Enables | OEAB and OEBA allow asymmetric bus control - e.g., A→B active while B→A isolated - enabling half-duplex arbitration |
| Power-Up High-Z | Guaranteed high-impedance on all I/O at VCC ramp-up - eliminates bus contention during cold start or hot-plug events |
| TTL-Compatible Interface | VIH/VIL thresholds match 74LS/74ALS families - no level-shifting needed in mixed-logic backplanes |
| Latch Mode (OEAB = OEBA = L) | Freezes A and B buses to identical states - useful for diagnostic hold, test mode, or glitch-free state capture |
Applications
| Industrial Backplane Interconnect | Legacy Telecom Line Card |
|---|---|
|
Use Scenario: Connecting CPU local bus to peripheral expansion slots in programmable logic controllers (PLCs) with hot-swap capability. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing data flow between processor and I/O modules; direction controlled by FPGA-generated OE signals. Use Value: Power-up high-Z prevents slot insertion faults; 48-mA drive sustains signal integrity across 15-cm ribbon-cable runs at 20-MHz burst rates. |
Use Scenario: Isolating microcontroller bus from DS0/DS1 framing ASICs in TDM-based access multiplexers. IC Role / Device Role / Timing Role: Asynchronous bus bridge synchronizing non-coherent clock domains; latch mode captures frame sync state during reconfiguration. Use Value: Dual OE logic allows independent enable of transmit/receive paths - eliminating need for external bus switches in full-duplex TDM channels. |
| Automated Test Equipment (ATE) Fixture | Avionics Data Acquisition Module |
|
Use Scenario: Routing stimulus/response signals between PXI controller and DUT interface boards in semiconductor burn-in testers. IC Role / Device Role / Timing Role: Reconfigurable bus coupler adapting tester's 5-V TTL bus to multiple DUT voltage standards via OE-controlled isolation. Use Value: 6.8-ns max tPHL ensures sub-10-ns timing margin for 100-MHz pattern generation; BiCMOS leakage <100 µA prevents fixture crosstalk. |
Use Scenario: Interfacing flight computer ARINC-429 receivers to local sensor preprocessing FPGA in regional jet avionics bays. IC Role / Device Role / Timing Role: Level-translating and isolating MIL-STD-1553B-compatible bus segments during power sequencing. Use Value: Guaranteed 0°C to 70°C operation meets DO-160 Category P thermal requirements; latch mode holds last valid sensor word during brownout recovery. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS29861N | Bipolar design; higher ICC (30–45 mA active); slower tPHL (10 ns typical); same pinout and logic function | Higher power dissipation limits density in compact modules; less suitable for thermally constrained telecom cards | Prefer SN74BCT29861BNT where board-level power budget < 2 W per transceiver or ambient > 60°C |
| Am29861A-25JC | AMD version; identical function and timing; rated for −40°C to +85°C; JEDEC-standard 24-pin ceramic DIP | Extended temperature range supports military/industrial environments; ceramic package improves thermal cycling reliability | Choose Am29861A-25JC only if extended temp or hermetic packaging is mandatory; otherwise SN74BCT29861BNT offers better cost/power trade-off |
Compared with SN74ALS29861N and Am29861A-25JC, SN74BCT29861BNT delivers optimal balance of low-power BiCMOS efficiency, commercial-temperature reliability, and drop-in compatibility - making it the preferred choice for cost-sensitive, space-constrained 5-V backplane designs requiring stable bus arbitration.
Availability
SN74BCT29861BNT is available at Aetrix Electronics and suitable for industrial backplane interconnect, legacy telecom line card upgrades, automated test equipment fixtures, and avionics data acquisition modules requiring stable component supply and long-term obsolescence management.
Supply support for SN74BCT29861BNT 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74BCT29861BNT belongs to TI's BCT (Bipolar-CMOS Transceiver) logic family, designed specifically to replace high-power bipolar bus transceivers in 5-V systems while preserving pin compatibility and logic behavior.
FAQ
What logic families is the SN74BCT29861BNT compatible with?
The SN74BCT29861BNT features TTL-compatible input thresholds (VIH = 2.0 V, VIL = 0.8 V) and outputs that drive standard TTL, LS, and ALS loads. It interfaces directly with 74LS, 74ALS, and earlier 74xx families without level shifters. Its BiCMOS output stage provides 48 mA sink current, supporting up to 20 standard TTL inputs per pin - confirmed in the recommended operating conditions and electrical characteristics tables of the SN74BCT29861BNT datasheet.
Does the SN74BCT29861BNT support hot-swap operation?
Yes, the SN74BCT29861BNT guarantees high-impedance outputs during power-up and power-down sequences, preventing bus contention when inserted into live backplanes. This behavior is explicitly documented in the device description and absolute maximum ratings section of the SN74BCT29861BNT datasheet, and is enabled by internal power-on reset circuitry independent of external control signals.
What is the function of the latch mode (OEAB = OEBA = L) in the SN74BCT29861BNT?
When both output-enable inputs are low, the SN74BCT29861BNT enters latch mode, forcing A1–A10 and B1–B10 to mirror each other's logic states regardless of subsequent input changes. This feature is used for diagnostic hold, state capture during fault conditions, or static bus configuration - and is defined in the FUNCTION TABLE of the SN74BCT29861BNT datasheet with "A = B" as the operational result.
Can the SN74BCT29861BNT operate at 3.3 V?
No, the SN74BCT29861BNT is specified only for 4.5 V to 5.5 V supply operation. Its input thresholds, output drive strength, and internal BiCMOS biasing are optimized for 5-V TTL systems. Attempting 3.3-V operation results in undefined logic levels, insufficient noise margin, and potential failure to meet VOH/VOL specifications - as confirmed by the recommended operating conditions table in the SN74BCT29861BNT datasheet.
How does the SN74BCT29861BNT differ from the SN74BCT29861DW?
The SN74BCT29861BNT and SN74BCT29861DW share identical electrical specifications, logic function, and pinout, differing only in package type: NT denotes 300-mil plastic DIP, while DW indicates SOIC-24. The NT package offers through-hole mounting and higher thermal mass for manual assembly or legacy PCBs; the DW package supports surface-mount automation and denser layouts - both are functionally interchangeable where mechanical constraints permit.
SN74BCT29861BNT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Number of Elements:
- -
- Number of Bits per Element:
- -
- Input Type:
- -
- Output Type:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
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- Mounting Type:
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SN74BCT29861BNT FAQ
1.How can I place an order for SN74BCT29861BNT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT29861BNT 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 SN74BCT29861BNT reliable?
The price and inventory of SN74BCT29861BNT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT29861BNT is usually 5 days.
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SN74BCT29861BNT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT29861BNT 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 SN74BCT29861BNT?
For technical support, including SN74BCT29861BNT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT29861BNT requirements.
6.How does Aetrix verify that SN74BCT29861BNT is sourced from the original manufacturer or authorized distributors?
All SN74BCT29861BNT 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 SN74BCT29861BNT meets industry standards.
7.What is the process for return or replacement of SN74BCT29861BNT?
All SN74BCT29861BNT units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT29861BNT, 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 SN74BCT29861BNT part is unused and in its original packaging.
Return procedure for SN74BCT29861BNT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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