My Inquiry
My Account
Texas Instruments SN74ALS29844NT
- Part No.:
- SN74ALS29844NT
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
SN74ALS29844NT.pdf
- Description:
- BUS DRIVER, ALS SERIES
- Quantity:
- Payment:
- Shipping:
Inventory:1,265
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SN74ALS29844NT from Texas Instruments is a 9-bit inverting D-type latch with three-state outputs, designed for bus interface applications in TTL-compatible systems. It operates at 4.75–5.25 V, delivers ±48 mA output drive, features power-up high-impedance, and supports 0°C to 70°C industrial temperature range - used in bidirectional bus drivers and I/O port expansion.
For engineers reviewing the SN74ALS29844NT datasheet, SN74ALS29844NT pinout, SN74ALS29844NT application, or SN74ALS29844NT equivalent, this page provides verified functional identity, bus-structured pin mapping, latch timing behavior under CL = 50 pF/300 pF loads, and direct alternatives for 9-bit inverting bus latching in legacy TTL designs.
Technical Context
The SN74ALS29844NT implements nine transparent D-type latches with inverted data inputs (D→Q̅), enabling synchronized storage of inverted bus signals. Its buffered OC input controls all nine outputs independently of internal latch state, allowing data retention during output disable.
It uses Advanced Low-Power Schottky (ALS) TTL technology, delivering 2.4 V VOH min at –24 mA and 0.5 V VOL max at 48 mA, with propagation delays as low as 2 ns (tPLH/tPHL, VCC = 5 V, TA = 25°C) and 3-state transition times under 9 ns (tPZL/tPHZ).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.75 V to 5.25 V - ensures compatibility with standard 5 V TTL supply rails and noise margin compliance. |
| Output Drive | –24 mA (IOH), +48 mA (IOL) - sufficient to drive heavily loaded buses without external buffers. |
| Propagation Delay | tPLH/tPHL ≤ 8 ns (CL = 50 pF) - enables reliable operation in high-speed bus timing budgets up to ~125 MHz clock-equivalent systems. |
| Three-State Enable Time | tPZL ≤ 12 ns, tPHZ ≤ 9 ns (CL = 50 pF) - guarantees fast bus release and acquisition for time-multiplexed address/data sharing. |
| Input Thresholds | VIH = 2.0 V, VIL = 0.8 V - matches standard TTL logic levels for seamless integration with 74LS/ALS families. |
| Power-Up State | Outputs default to high-impedance - prevents bus contention during system reset or cold start. |
| Operating Temperature | 0°C to 70°C - qualified for commercial and industrial control equipment environments. |
Pinout & Package
SN74ALS29844NT is supplied in a 24-pin plastic dual in-line package (PDIP), designated NT package by Texas Instruments. Pin numbering follows standard DIP top-view orientation with pin 1 at top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8, 9 | Inverting Data Inputs (1D–9D) | Accept parallel data; each input inverted internally before latching - enables direct connection to non-inverted bus sources requiring complemented storage. |
| 10 | Output Control (OC) | Active-low enable; when low, outputs reflect latched Q values; when high, all outputs enter high-Z - decouples latch state from bus activity. |
| 11, 12 | Presets (PRE) & Clears (CLR) | Asynchronous active-low controls - PRE forces all Q outputs high, CLR forces all Q outputs low, independent of clock or OC. |
| 13 | GND | Ground reference for all inputs, outputs, and internal circuitry - must be low-impedance connection to minimize ground bounce in bus-driving applications. |
| 14, 15, 16, 17, 18, 19, 20, 21, 22 | Inverted Latched Outputs (1Q–9Q) | Three-state outputs reflecting inverted D-input state at last C↑ edge - drive bus lines directly with TTL-compatible voltage levels and current capability. |
| 23 | Clock (C) | Positive-edge-triggered latch enable - data on D inputs is captured on rising edge and held until next C↑ or asynchronous PRE/CLR assertion. |
| 24 | VCC | +5 V supply pin - requires local 0.1 µF ceramic bypass capacitor to GND to suppress switching noise during high-current output transitions. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting D-type latch architecture | Directly stores and outputs logical complements of input bus data - eliminates need for external inverters in parity generation or sign-extension paths. |
| Bus-structured pinout | Input and output pins arranged in parallel order (1D–9D / 1Q–9Q) - simplifies PCB routing for wide data/address buses and reduces trace skew. |
| Buffered OC and control inputs | Reduces DC loading on upstream drivers - allows single OC signal to manage nine outputs without fanout degradation or timing skew. |
| Power-up high-impedance | Prevents bus conflicts at power-on reset - critical for hot-swap-capable backplanes and multi-master bus arbitration. |
| ALS TTL process | Combines Schottky-clamped speed with low power consumption - achieves 8 ns propagation delay with 85 mA ICC max, outperforming standard LS in speed/power ratio. |
Applications
| Memory Address Latching | I/O Port Expansion |
|---|---|
Use Scenario: Latching 9-bit address segments in 8080/Z80-based microcomputer systems where address bus must be held stable during memory access cycles. IC Role / Device Role / Timing Role: SN74ALS29844NT captures and holds inverted address bits on C↑, then drives them onto the bus via three-state outputs controlled by OC synchronized to memory enable. Use Value: Enables clean separation of address setup and hold timing while supporting bus sharing with peripherals - avoids external pull-ups or level shifters due to native TTL drive strength. | Use Scenario: Expanding parallel I/O capability in industrial PLC modules requiring isolated, high-drive digital outputs for relay or LED bank control. IC Role / Device Role / Timing Role: SN74ALS29844NT acts as an output port latch: microcontroller writes inverted control codes to D inputs, then pulses C to store; OC enables/disables output drive to field devices. Use Value: Provides 48 mA per output - sufficient to drive LEDs or small relays directly - and high-impedance disable prevents backfeeding during configuration or fault conditions. |
| Parity Bus Interface | Legacy Backplane Interfacing |
Use Scenario: Generating and latching odd/even parity bits across 8-bit data buses in telecom line cards using separate parity check logic. IC Role / Device Role / Timing Role: SN74ALS29844NT receives parity generator outputs (inverted logic), latches them on C↑, and presents them on three-state outputs aligned with data bus timing. Use Value: Inverting inputs match common open-collector parity generator outputs - eliminates discrete inverters and reduces component count and propagation delay in parity path. | Use Scenario: Interfacing modern controllers to vintage VME or Multibus I backplanes requiring TTL-level, high-drive, three-state address/data transceivers. IC Role / Device Role / Timing Role: SN74ALS29844NT serves as a unidirectional address latch: captures CPU address on C↑, holds it stable, and drives it onto backplane with OC coordinated to bus grant timing. Use Value: ALS speed and 48 mA drive meet strict VME A16/A24 timing requirements; bus-structured pinout aligns with backplane connector layouts - minimizing layer count and stub length. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 9-bit inverting bus latch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS29843NT | Non-inverting D inputs; otherwise identical timing, drive, and pinout. | Used where bus data must be latched without inversion - e.g., direct data path buffering without sign extension or parity complement. | Select SN74ALS29843NT when input-to-output polarity must be preserved; SN74ALS29844NT only when inversion is required or already present upstream. |
| SN74F29844N | Fast TTL version: faster propagation (≤5 ns), higher ICC (110 mA), no guaranteed power-up high-Z. | Suitable for speed-critical systems where bus contention risk during startup is mitigated by system-level reset sequencing. | Choose SN74F29844N for maximum speed in non-cold-start environments; retain SN74ALS29844NT where power-up safety and lower power are prioritized. |
Compared with SN74ALS29843NT and SN74F29844N, the SN74ALS29844NT uniquely combines inverting logic, guaranteed power-up high-impedance, and ALS power efficiency - making it optimal for legacy bus interfaces where polarity alignment and startup robustness are mandatory.
Availability
SN74ALS29844NT is available at Aetrix Electronics and suitable for memory address latching, I/O port expansion, parity bus interfacing, and legacy backplane interfacing requiring stable component supply and long-term obsolescence support.
Supply support for SN74ALS29844NT 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 qualification.
The SN74ALS29844NT belongs to TI's Advanced Low-Power Schottky (ALS) TTL logic family, engineered for high-speed, low-power bus interface applications in retro-computing, industrial control, and military-grade legacy systems.
FAQ
What logic function does the SN74ALS29844NT implement?
The SN74ALS29844NT implements nine independent inverting D-type transparent latches with three-state outputs. Each D input is inverted before being latched on the rising edge of the clock (C), and the resulting Q outputs are inverted relative to D. This allows direct use with open-collector parity generators or sign-extension paths without external inverters. The SN74ALS29844NT maintains full functional equivalence to its non-inverting counterpart SN74ALS29843NT except for input/output polarity.
Does the SN74ALS29844NT have guaranteed power-up high-impedance behavior?
Yes, the SN74ALS29844NT guarantees high-impedance outputs during power-up and power-down sequences. This behavior is inherent to its ALS TTL design and is explicitly specified in the datasheet - preventing bus contention when the device powers on before or after other bus components. Unlike some Fast TTL variants, the SN74ALS29844NT does not require external pull-up/pull-down networks to ensure safe startup states.
What is the maximum capacitive load the SN74ALS29844NT can drive reliably?
The SN74ALS29844NT is characterized for reliable operation with capacitive loads up to 300 pF, as confirmed by switching specifications at CL = 300 pF (e.g., tPLH ≤ 14 ns, tPZL ≤ 14 ns). Its ±48 mA output drive ensures signal integrity across long traces or multiple TTL inputs. For loads exceeding 300 pF, derating of timing margins or addition of series termination may be necessary - but the SN74ALS29844NT itself does not require external drivers under typical backplane or motherboard bus conditions.
Can the SN74ALS29844NT be used alongside SN74ALS29843NT on the same bus?
Yes, the SN74ALS29844NT and SN74ALS29843NT share identical pinouts, timing, drive strength, and electrical characteristics - differing only in input inversion. They can coexist on the same bus when controlled by a common OC signal and clock, enabling mixed-function latching (e.g., inverting parity + non-inverting address). Because both devices are ALS TTL, their voltage thresholds and noise margins are fully compatible, and no level-shifting is needed when using the SN74ALS29844NT alongside SN74ALS29843NT.
What package type does the SN74ALS29844NT use, and is it RoHS-compliant?
The SN74ALS29844NT uses a 24-pin plastic dual in-line package (PDIP), designated NT by Texas Instruments. This through-hole package is widely used in legacy industrial and test equipment. As a pre-RoHS-era component manufactured prior to 2006, the SN74ALS29844NT contains lead in solder and die attach materials and is not RoHS-compliant; however, it remains available under exemption clauses for legacy repair and obsolescence management programs. Aetrix Electronics provides full traceability and documentation for the SN74ALS29844NT's material composition upon request.
SN74ALS29844NT 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:
- -
- Supplier Device Package:
- -
SN74ALS29844NT FAQ
1.How can I place an order for SN74ALS29844NT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS29844NT 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 SN74ALS29844NT reliable?
The price and inventory of SN74ALS29844NT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS29844NT is usually 5 days.
3.What payment methods are accepted for SN74ALS29844NT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS29844NT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS29844NT?
SN74ALS29844NT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS29844NT 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 SN74ALS29844NT?
For technical support, including SN74ALS29844NT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS29844NT requirements.
6.How does Aetrix verify that SN74ALS29844NT is sourced from the original manufacturer or authorized distributors?
All SN74ALS29844NT 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 SN74ALS29844NT meets industry standards.
7.What is the process for return or replacement of SN74ALS29844NT?
All SN74ALS29844NT units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS29844NT, 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 SN74ALS29844NT part is unused and in its original packaging.
Return procedure for SN74ALS29844NT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74ALS29844NT Tags
-
SN74LVC1G17DBVR
Texas Instruments
-
SN74LVC1G07DCKR
Texas Instruments
-
SN74LVC1G17DCKR
Texas Instruments
-
SN74LVC1G07DBVR
Texas Instruments
-
SN74LVC1G125DCKR
Texas Instruments
-
SN74AHCT1G126DBVR
Texas Instruments
-
SN74LVC1G125DBVR
Texas Instruments
-
SN74AHCT1G125DBVR
Texas Instruments
-
SN74LVC2G17DBVR
Texas Instruments
-
SN74LVC2G07DCKR
Texas Instruments
-
SN74LVC1G34DCKR
Texas Instruments
-
SN74LVC2G17DCKR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
