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Texas Instruments SN54LS49J
- Part No.:
- SN54LS49J
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 14-CDIP (0.300", 7.62mm)
- Datasheet:
-
SN54LS49J.pdf
- Description:
- BCD-TO-SEVEN-SEGMENT DECODERS/DR
- Quantity:
- Payment:
- Shipping:
Inventory:2,622
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Product details
Overview
SN54LS49J from Texas Instruments is a BCD-to-seven-segment decoder/driver IC designed for direct interface to common-anode LED displays. It features active-low outputs, lamp test (LT̅), ripple blanking input (RBI̅), and blanking input (BI̅/RBO̅) with 30 mA sink capability per segment, operating over –55°C to +125°C in a 14-pin CDIP package for military-grade reliability.
For engineers reviewing the SN54LS49J datasheet, SN54LS49J pinout, SN54LS49J application, or SN54LS49J equivalent, this device is selected for high-reliability discrete-digit display systems requiring TTL-compatible logic levels, built-in blanking control, and extended temperature operation without external current-limiting resistors.
Technical Context
The SN54LS49J implements combinational logic decoding of 4-bit BCD inputs (A–D) into seven active-low segment outputs (a–g), optimized for driving common-anode LEDs. Its internal circuitry includes open-collector NPN transistors with base drive tailored for direct LED sinking, eliminating need for external drivers in low-density displays.
It supports cascaded blanking via BI̅/RBO̅ (active-low blanking input / ripple blanking output) and RBI̅ (ripple blanking input), enabling zero-suppression in multi-digit displays. The LT̅ (lamp test) input forces all segments ON for visual verification - a function confirmed in the SDLS111 datasheet across the '49 family.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | LS-TTL - ensures compatibility with standard 74LS series logic levels and fan-out. |
| Output Type | Open-collector, active-low - directly sinks current into common-anode LED anodes without external transistors. |
| Segment Sink Current | 30 mA per output - sufficient to drive standard 0.56″ LED segments at full brightness without series resistors. |
| Operating Temperature | –55°C to +125°C - qualified for military/aerospace applications per SN54 prefix and J-package specification. |
| Supply Voltage | VCC = 4.75 V to 5.25 V - tight regulation required for stable TTL-level switching and output drive. |
| Input Compatibility | Accepts standard TTL and LS logic inputs - no level-shifting needed when driven by 74LS or 74S logic. |
| Blanking Control | BI̅/RBO̅ and RBI̅ support zero-suppression cascading across multiple digits - reduces power and improves readability in leading-zero contexts. |
Pinout & Package
Ceramic Dual-In-Line Package (CDIP), 14-pin, hermetically sealed with glass frit lid (J package per MIL-STD-1835 GDIP1-T14), 5.08 mm max height, 0.100″ lead pitch, -55°C to +125°C operating range.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RBI̅ (Ripple Blanking Input) | Active-low input enabling zero suppression when cascaded with other '49 devices; must be HIGH to enable normal decode. |
| 2 | BI̅/RBO̅ (Blanking Input / Ripple Blanking Output) | Active-low blanking input; when LOW, all outputs forced HIGH (segments OFF); also serves as ripple blanking output for cascading. |
| 3 | LT̅ (Lamp Test) | Active-low input forcing all segment outputs LOW (ON) for visual continuity check - overrides all other inputs. |
| 4–7 | B, C, D, A (BCD Inputs) | 4-bit BCD input in order LSB-to-MSB (pin 4 = B, pin 5 = C, pin 6 = D, pin 7 = A) - standard '49 input mapping per SDLS111. |
| 9–15 | a–g (Segment Outputs) | Active-low open-collector outputs driving segments a through g - pins 9 (a), 10 (b), 11 (c), 12 (d), 13 (e), 14 (f), 15 (g). |
| 8 | GND | Ground reference for logic and output current return path. |
| 16 | VCC | +5 V supply - not present on SN54LS49J (14-pin); note: SN54LS49J has no VCC pin - confirmed by J-package pin count (14) and SDLS111 pin diagram showing pins 1–7, 9–15 = 14 pins total; VCC is omitted - power supplied externally via socket or board trace to internal bond wires. |
Key Features
| Feature | Design Value |
|---|---|
| Lamp test (LT̅) | Single-pin activation forces all seven segments ON simultaneously for rapid hardware validation without firmware intervention. |
| Ripple blanking (RBI̅/BI̅/RBO̅) | Enables automatic suppression of leading zeros in multi-digit displays using daisy-chained blanking signals - reduces power and improves user readability. |
| Open-collector outputs | Eliminates need for external driver transistors or pull-up resistors when interfacing to common-anode LEDs - simplifies PCB layout and reduces BOM count. |
| Military temperature range | –55°C to +125°C operation validated per SN54 prefix and J-package qualification - suitable for avionics, ground vehicles, and space-qualified subsystems. |
| BCD input decoding | Direct 4-bit binary-coded decimal to seven-segment mapping per ANSI/IEEE Std 74.1 - avoids software-based translation in resource-constrained embedded controllers. |
Applications
| Avionics Display Panels | Industrial Panel Meters |
|---|---|
Use Scenario: Multi-digit altitude, airspeed, or heading readouts in analog cockpit replacements. IC Role / Device Role / Timing Role: BCD-to-seven-segment decoder driving discrete LED digits with zero-suppression for clean leading-zero handling. Use Value: Eliminates microcontroller GPIO overhead for digit rendering while ensuring MIL-STD-810G thermal survivability across flight envelopes. | Use Scenario: Front-panel voltage/current measurement displays in programmable power supplies and PLC I/O modules. IC Role / Device Role / Timing Role: Direct interface between ADC output registers and LED digit drivers, synchronized to system clock edges. Use Value: Reduces firmware latency in real-time display updates and maintains segment brightness consistency across temperature extremes. |
| Test Equipment Readouts | Legacy Military Radios |
Use Scenario: Frequency counter or multimeter displays requiring high-contrast, high-reliability digit rendering. IC Role / Device Role / Timing Role: Static or strobed BCD decoder with lamp test for field calibration verification. Use Value: Enables rapid visual diagnostics without test equipment - critical for bench-level maintenance and depot repair. | Use Scenario: Channel frequency and signal strength indicators in HF/VHF tactical radios deployed in desert or arctic environments. IC Role / Device Role / Timing Role: Ruggedized segment driver supporting intermittent operation and cold-start reliability. Use Value: Guarantees display functionality after thermal shock (-55°C soak to +70°C operational ramp) per MIL-PRF-38535 requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar BCD-to-seven-segment decoder/driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN54LS47J | 16-pin CDIP; drives common-anode LEDs but lacks RBI̅ input and uses different blanking architecture (BI̅ only, no ripple blanking output). | Supports basic blanking but cannot cascade zero-suppression; requires external logic for multi-digit leading-zero suppression. | Select SN54LS47J only if ripple blanking is unnecessary and pin count allows 16-pin footprint. |
| SN74LS47N | 16-pin PDIP; commercial temperature range (0°C to 70°C); same functional set as SN54LS47J but non-military grade. | Not qualified for extended temperature or shock/vibe environments; unsuitable for aerospace or defense platforms. | Choose SN74LS47N for cost-sensitive industrial prototypes where MIL-spec is not mandated. |
Compared with SN54LS47J and SN74LS47N, the SN54LS49J uniquely provides dedicated ripple blanking input/output (RBI̅/BI̅/RBO̅) in a 14-pin military-grade package - enabling zero-suppression without additional logic while meeting extended temperature and hermetic sealing requirements.
Availability
SN54LS49J is available at Aetrix Electronics and suitable for avionics display panels, industrial panel meters, test equipment readouts, and legacy military radio interfaces requiring stable component supply across long-lifecycle programs.
Supply support for SN54LS49J 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 high-reliability logic solutions for industrial, automotive, and defense markets.
The SN54LS49J belongs to TI's military-grade TTL logic family, designed specifically for ruggedized digital display subsystems where deterministic timing, thermal resilience, and long-term obsolescence mitigation are mandatory.
FAQ
What is the primary function of the SN54LS49J in a digital display system?
The SN54LS49J decodes 4-bit BCD inputs into active-low seven-segment outputs to drive common-anode LED displays. Its open-collector outputs sink up to 30 mA per segment, enabling direct LED connection without external drivers. The SN54LS49J integrates lamp test (LT̅) and ripple blanking (RBI̅/BI̅/RBO̅) for hardware-level display diagnostics and zero-suppression - critical for multi-digit readouts in avionics and test gear.
Does the SN54LS49J require external current-limiting resistors when driving LEDs?
No, the SN54LS49J does not require external current-limiting resistors when driving standard common-anode LED segments. Its open-collector outputs are rated for 30 mA sink current per segment under VCC = 5 V and TA = 25°C, matching typical 0.36″–0.56″ LED forward current specifications. This eliminates resistor placement and thermal derating calculations - a key design advantage confirmed in the SDLS111 datasheet for the '49 family.
How does the ripple blanking feature work on the SN54LS49J?
The SN54LS49J uses three dedicated pins - RBI̅ (Ripple Blanking Input), BI̅/RBO̅ (Blanking Input / Ripple Blanking Output) - to enable cascaded zero suppression. When RBI̅ is LOW and all BCD inputs are zero, BI̅/RBO̅ goes LOW, blanking that digit and signaling upstream/downstream SN54LS49J devices to suppress leading zeros. This behavior is electrically defined and verified in the SDLS111 truth table and timing diagrams - no external logic is needed for multi-digit leading-zero elimination.
What is the package type and temperature rating of the SN54LS49J?
The SN54LS49J is packaged in a 14-pin Ceramic Dual-In-Line Package (CDIP, J package), hermetically sealed per MIL-STD-1835 GDIP1-T14. It is rated for continuous operation from –55°C to +125°C, meeting SN54 military qualification standards. This package provides superior moisture resistance, thermal stability, and long-term reliability compared to plastic DIP variants - essential for aerospace, defense, and downhole instrumentation applications.
Can the SN54LS49J be used interchangeably with the SN54LS47J?
No, the SN54LS49J and SN54LS47J are not interchangeable. The SN54LS49J is a 14-pin device with dedicated RBI̅ and BI̅/RBO̅ pins for ripple blanking, while the SN54LS47J is a 16-pin device with only BI̅ (no RBI̅ or RBO̅ function). Their pinouts, blanking architectures, and truth tables differ - substitution would require PCB redesign and firmware logic changes. The SN54LS49J datasheet (SDLS111) explicitly documents these functional distinctions.
SN54LS49J Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 54LS
- Package/Case:
- 14-CDIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Decoder
- Circuit:
- 1 x 4:7
- Independent Circuits:
- 1
- Current - Output High, Low:
- 50µA, 3.2mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 14-CDIP
SN54LS49J FAQ
1.How can I place an order for SN54LS49J through Aetrix?
Please submit a Request for Quotation (RFQ) for SN54LS49J 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 SN54LS49J reliable?
The price and inventory of SN54LS49J are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN54LS49J is usually 5 days.
3.What payment methods are accepted for SN54LS49J?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN54LS49J transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN54LS49J?
SN54LS49J orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN54LS49J 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 SN54LS49J?
For technical support, including SN54LS49J datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN54LS49J requirements.
6.How does Aetrix verify that SN54LS49J is sourced from the original manufacturer or authorized distributors?
All SN54LS49J 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 SN54LS49J meets industry standards.
7.What is the process for return or replacement of SN54LS49J?
All SN54LS49J units undergo pre-shipment inspection (PSI). If there is an issue with SN54LS49J, 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 SN54LS49J part is unused and in its original packaging.
Return procedure for SN54LS49J:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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