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Home > Products > Integrated Circuits (ICs) > Logic > Buffers, Drivers, Receivers, Transceivers

Texas Instruments SN74BCT29846NT

Name: SN74BCT29846NT
Brand: Texas Instruments
SKU: SN74BCT29846NT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74BCT29846NT

Manufacturer:: Texas Instruments

Category:: Buffers, Drivers, Receivers, Transceivers

Package:: -

Datasheet:: SN74BCT29846NT.pdf

Description:: BUS DRIVER, BCT/FBT SERIES

Quantity:: RFQ Add To RFQ list

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Product details

Overview

SN74BCT29846NT from Texas Instruments is an octal transparent D-type latch with inverting data inputs, 3-state outputs, and independent preset/clear controls. It operates at 4.5–5.5 V, delivers ±48 mA output drive, features bus-structured pinout, and supports 0°C to 70°C industrial temperature range - ideal for bidirectional bus drivers and I/O port buffering in legacy TTL/CMOS hybrid systems.

For engineers reviewing the SN74BCT29846NT datasheet, SN74BCT29846NT pinout, SN74BCT29846NT application, or SN74BCT29846NT equivalent, key selection considerations include its BiCMOS process enabling low standby current, buffered OE inputs reducing DC loading, power-up high-impedance state, and functional equivalence to SN74ALS29846 and Am29846.

Technical Context

The SN74BCT29846NT implements eight independent transparent latches with asynchronous preset (PRE) and clear (CLR), both active-low and independent of latch-enable (LE). Its BiCMOS architecture combines CMOS inputs with TTL-compatible outputs, delivering 24 mA sink and −15 mA source capability under 5 V operation.

Three buffered output-enable inputs (OE1, OE2, OE3) control simultaneous 3-state output behavior without affecting internal latch states. The device enters high-impedance on power-up/down and maintains output isolation during disable, eliminating need for external pull-ups in bus-organized systems.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage	4.5 V to 5.5 V - ensures compatibility with standard 5 V TTL/CMOS logic rails and stable operation across supply tolerance.
Output Drive	±48 mA (IOL), −24 mA (IOH) - enables direct driving of heavy capacitive loads or multiple TTL inputs without external buffers.
Propagation Delay	1.5–9 ns (D→Q), 2–15 ns (OE→Q) - supports high-speed bus arbitration and latch timing in 20+ MHz system designs.
Input Thresholds	VIL = 0.8 V, VIH = 2.0 V - guarantees reliable interfacing with both CMOS and TTL logic families.
Operating Temperature	0°C to 70°C - validated for commercial-grade embedded control, instrumentation, and industrial backplane applications.
Power-Up State	Outputs default to high-impedance - prevents bus contention during system reset or cold start sequences.

Pinout & Package

Packaged in standard plastic 300-mil DIP (NT), the SN74BCT29846NT uses a bus-structured 24-pin layout optimized for parallel data path routing and minimal trace skew.

Pin/Terminal	Circuit Role	Design Meaning
1, 13, 14	OE1, OE2, OE3	Buffered 3-state enable inputs - all three must be low to activate outputs; high-impedance when any is high.
2–9	1D–8D	Inverting data inputs - logic low at input produces high at Q output when latched.
11	CLR	Asynchronous clear - active-low, forces all Q outputs low regardless of LE or PRE state.
15–22	1Q–8Q	3-state complementary outputs - reflect inverted D input when enabled and latched; high-Z otherwise.
23	PRE	Asynchronous preset - active-low, forces all Q outputs high independently of CLR or LE.
10	LE	Latch-enable - transparent mode when high; latches D-input state on falling edge.

Key Features

Feature	Design Value
BiCMOS Process	Reduces standby ICC to 3–7 mA vs. 24–35 mA active - cuts quiescent power by >80% in idle bus buffer configurations.
Bus-Structured Pinout	Groups inputs (D1–D8) and outputs (Q1–Q8) contiguously - simplifies PCB layout for 8-bit parallel interfaces and minimizes signal crosstalk.
Independent PRE/CLR	Allows deterministic initialization of all outputs to known high or low state without clock or latch-enable dependency.
Power-Up High-Z	Eliminates bus conflicts during power sequencing - no external pull-up resistors required for safe hot-insertion or multi-voltage domain systems.
Buffered Control Inputs	Reduces input loading to ≤0.2 mA per OE/LE/CLR - preserves signal integrity when driving from weak microcontroller GPIOs.

Applications

Legacy Bus Interface	Industrial I/O Expansion
Use Scenario: Interfacing 8-bit microprocessor address/data buses to peripheral devices with mismatched voltage or drive requirements. IC Role / Device Role / Timing Role: Bidirectional bus driver and latch register providing level translation and load isolation between CPU and slower peripherals. Use Value: Enables direct connection to TTL loads while maintaining CMOS input compatibility and eliminating external interface logic.	Use Scenario: Adding isolated, latched digital I/O ports to PLC or motion controller backplanes operating in electrically noisy environments. IC Role / Device Role / Timing Role: Input capture and output staging register with asynchronous reset/preset for deterministic startup and fault recovery. Use Value: Provides noise-immune data retention during transient resets and allows synchronized output updates via shared LE signal.
Memory Address Latching	Test Equipment Signal Conditioning
Use Scenario: Latching upper address bits in 16-bit memory systems where lower bits are multiplexed with data lines. IC Role / Device Role / Timing Role: Transparent latch holding stable address segments during DRAM row/column access cycles. Use Value: Meets tight setup/hold timing (tsu = 1.5 ns, th = 3.5 ns) for high-speed memory controllers without added delay stages.	Use Scenario: Buffering and isolating stimulus/response signals in automated test equipment (ATE) fixture interfaces. IC Role / Device Role / Timing Role: 3-state signal conditioner enabling shared test bus access across multiple DUT channels. Use Value: Prevents channel crosstalk via high-impedance disable and supports hot-swappable module insertion without bus disruption.

Legacy Bus Interface

Industrial I/O Expansion

Use Scenario: Interfacing 8-bit microprocessor address/data buses to peripheral devices with mismatched voltage or drive requirements.

IC Role / Device Role / Timing Role: Bidirectional bus driver and latch register providing level translation and load isolation between CPU and slower peripherals.

Use Value: Enables direct connection to TTL loads while maintaining CMOS input compatibility and eliminating external interface logic.

Use Scenario: Adding isolated, latched digital I/O ports to PLC or motion controller backplanes operating in electrically noisy environments.

IC Role / Device Role / Timing Role: Input capture and output staging register with asynchronous reset/preset for deterministic startup and fault recovery.

Use Value: Provides noise-immune data retention during transient resets and allows synchronized output updates via shared LE signal.

Memory Address Latching

Test Equipment Signal Conditioning

Use Scenario: Latching upper address bits in 16-bit memory systems where lower bits are multiplexed with data lines.

IC Role / Device Role / Timing Role: Transparent latch holding stable address segments during DRAM row/column access cycles.

Use Value: Meets tight setup/hold timing (tsu = 1.5 ns, th = 3.5 ns) for high-speed memory controllers without added delay stages.

Use Scenario: Buffering and isolating stimulus/response signals in automated test equipment (ATE) fixture interfaces.

IC Role / Device Role / Timing Role: 3-state signal conditioner enabling shared test bus access across multiple DUT channels.

Use Value: Prevents channel crosstalk via high-impedance disable and supports hot-swappable module insertion without bus disruption.

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal latch with 3-state output applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74ALS29846N	Same function and pinout but built in ALS bipolar process - higher ICC (25–45 mA active), slower propagation (typ. 10 ns), no BiCMOS standby current reduction.	Limited to lower-frequency systems (<10 MHz) due to increased propagation delay and power dissipation.	Choose when legacy ALS compatibility is required and thermal budget permits higher active power.
Am29846PC	AMD version with identical logic function and timing; minor differences in VOH/VOL specs (VOH min = 2.4 V @ IOH = −15 mA vs. TI's 2.0 V).	May require validation for marginal VIH margin in mixed-logic systems near 2.0 V threshold.	Acceptable drop-in alternative where AMD-sourced components are preferred in existing BOMs.

Compared with SN74ALS29846N and Am29846PC, the SN74BCT29846NT offers superior power efficiency in standby, faster switching, and tighter output voltage margins - making it optimal for thermally constrained or battery-backed industrial control modules requiring reliable bus hold during sleep modes.

Availability

SN74BCT29846NT is available at Aetrix Electronics and suitable for legacy system repair, industrial I/O expansion, memory address latching, and test equipment signal conditioning requiring stable component supply and long-term obsolescence management.

Supply support for SN74BCT29846NT 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 SN74BCT29846NT belongs to TI's BCT logic family - designed specifically for high-drive, low-power bus interface applications in mixed-technology systems requiring TTL output compatibility with CMOS input thresholds.

FAQ

What is the primary function of the SN74BCT29846NT in a digital system?

The SN74BCT29846NT functions as an octal transparent D-type latch with 3-state outputs, used to buffer, isolate, and temporarily store 8-bit parallel data. Its inverting data inputs, independent preset/clear, and bus-structured pinout make it especially suited for bidirectional bus driving and I/O port expansion. The SN74BCT29846NT supports clean signal handoff between subsystems with differing drive strengths or voltage domains.

Does the SN74BCT29846NT support hot-plug or power sequencing without bus contention?

Yes - the SN74BCT29846NT enters a high-impedance state during power-up and power-down, preventing output contention on shared buses. This behavior is inherent to its design and requires no external circuitry. The SN74BCT29846NT maintains this safe state until VCC stabilizes and control inputs settle, making it suitable for modular backplane architectures.

How does the BiCMOS process benefit the SN74BCT29846NT compared to standard TTL or ALS logic?

The BiCMOS process in the SN74BCT29846NT combines CMOS input stages with bipolar output drivers, achieving TTL-compatible output levels and drive strength while reducing standby current to just 3–7 mA. This improves power efficiency over ALS variants like SN74ALS29846N, which draw 25–45 mA actively and lack low-quiescent operation - a critical advantage in thermally sensitive or energy-constrained designs using the SN74BCT29846NT.

Can the SN74BCT29846NT be used with both 3.3 V and 5 V logic families?

The SN74BCT29846NT is specified for 4.5–5.5 V operation and has CMOS-compatible input thresholds (VIH = 2.0 V, VIL = 0.8 V), allowing reliable interfacing with 5 V TTL and CMOS. However, it is not 3.3 V tolerant: applying 3.3 V logic levels directly to inputs risks violating VIH minimum under worst-case conditions. For mixed-voltage systems, level-shifting or voltage translation is required before connecting to 3.3 V sources driving the SN74BCT29846NT.

What is the significance of the "bus-structured pinout" mentioned in the SN74BCT29846NT datasheet?

The bus-structured pinout groups related signals - D1–D8 on pins 2–9 and Q1–Q8 on pins 15–22 - to minimize trace length and skew in parallel data paths. This layout simplifies PCB routing for 8-bit interfaces, reduces crosstalk, and supports clean timing alignment across all bits. The SN74BCT29846NT's pin arrangement is optimized for direct connection to microprocessor data/address buses without interleaved signal routing.

SN74BCT29846NT 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:: -

Mounting Type:: -

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SN74BCT29846NT FAQ

1.How can I place an order for SN74BCT29846NT through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74BCT29846NT 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 SN74BCT29846NT reliable?

The price and inventory of SN74BCT29846NT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT29846NT is usually 5 days.

3.What payment methods are accepted for SN74BCT29846NT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74BCT29846NT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74BCT29846NT?

SN74BCT29846NT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74BCT29846NT 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 SN74BCT29846NT?

For technical support, including SN74BCT29846NT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT29846NT requirements.

6.How does Aetrix verify that SN74BCT29846NT is sourced from the original manufacturer or authorized distributors?

All SN74BCT29846NT 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 SN74BCT29846NT meets industry standards.

7.What is the process for return or replacement of SN74BCT29846NT?

All SN74BCT29846NT units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT29846NT, 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 SN74BCT29846NT part is unused and in its original packaging.

Return procedure for SN74BCT29846NT:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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