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Texas Instruments CD40147BMT
- Part No.:
- CD40147BMT
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
CD40147BMT.pdf
- Description:
- IC PRIORITY ENCOD 10X1:4 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,579
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Product details
Overview
CD40147BMT from Texas Instruments is a CMOS 10-line-to-4-line priority encoder IC that converts active-high decimal inputs (0–9) into active-low BCD outputs (8, 4, 2, 1), with line 9 assigned highest priority. It operates over –55°C to +125°C, drives one TTL low-power Schottky load per output, and features fully buffered I/O. It is used in keyboard encoding and fault-tolerant input scanning systems where only the highest asserted digit must be encoded.
For engineers reviewing the CD40147BMT datasheet, CD40147BMT pinout, CD40147BMT application, or CD40147BMT equivalent, key selection considerations include priority encoding behavior, active-low BCD output polarity, TTL-load drive capability, wide temperature range support, and SOIC-16 packaging compatibility with legacy 74147-based designs when pin 15 is grounded.
Technical Context
The CD40147BMT implements a fixed-priority logic architecture where input line 9 dominates all lower-numbered lines (8 through 0); only the highest-active input determines the BCD output state. Its internal logic ensures deterministic encoding without race conditions or metastability under asynchronous input assertion.
All four BCD outputs are actively pulled low for valid encoding and float high (logic 1 at VSS) only when all ten inputs are inactive (logic 0). Input and output buffers provide noise immunity and standardized drive strength, enabling direct interface with TTL and other CMOS logic families.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Encoding Type | Priority encoder: only highest-order active input (0–9) produces valid BCD output |
| Input Count / Output Format | 10 active-high inputs → 4-bit active-low BCD (8, 4, 2, 1) |
| Supply Voltage Range | 3 V to 18 V - supports mixed-voltage system interfacing and battery-powered operation |
| Output Drive Capability | One TTL low-power Schottky load per output - enables direct fanout to standard TTL without level-shifting |
| Operating Temperature | –55°C to +125°C - qualified for extended industrial and automotive under-hood environments |
| Logic Family | CMOS - provides high noise immunity, low static power consumption, and rail-to-rail input voltage tolerance |
Pinout & Package
CD40147BMT is supplied in a 16-lead small-outline integrated circuit (SOIC) package (D suffix), measuring 8 mm × 5.3 mm × 1.75 mm, with 1.27 mm pitch and gull-wing leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Input 0 | Lowest-priority active-high decimal input; asserted only if inputs 1–9 are inactive |
| 2 | Input 1 | Active-high decimal input with priority above input 0, below input 2 |
| 3 | Input 2 | Active-high decimal input with priority above inputs 0–1, below input 3 |
| 4 | Input 3 | Active-high decimal input with priority above inputs 0–2, below input 4 |
| 5 | Input 4 | Active-high decimal input with priority above inputs 0–3, below input 5 |
| 6 | Input 5 | Active-high decimal input with priority above inputs 0–4, below input 6 |
| 7 | Input 6 | Active-high decimal input with priority above inputs 0–5, below input 7 |
| 8 | Input 7 | Active-high decimal input with priority above inputs 0–6, below input 8 |
| 9 | Input 8 | Active-high decimal input with priority above inputs 0–7, below input 9 |
| 10 | Input 9 | Highest-priority active-high decimal input; overrides all others when asserted |
| 11 | Output 1 (LSB) | Active-low BCD bit 1; low when encoded value includes bit 1 (e.g., digits 1,3,5,7,9) |
| 12 | Output 2 | Active-low BCD bit 2; low when encoded value includes bit 2 (e.g., digits 2,3,6,7) |
| 13 | Output 4 | Active-low BCD bit 4; low when encoded value includes bit 4 (e.g., digits 4–7) |
| 14 | Output 8 (MSB) | Active-low BCD bit 8; low only for digit 8 or 9 |
| 15 | Enable/Ground | Must be tied low (VSS) to enable encoding; floating or high disables outputs (all high) |
| 16 | VDD | Positive supply terminal; accepts 3 V to 18 V DC |
Key Features
| Feature | Design Value |
|---|---|
| Priority encoding logic | Guarantees single-output resolution even when multiple inputs are simultaneously active - eliminates ambiguous states in keypad or switch matrix interfaces |
| Active-low BCD outputs | Directly compatible with common-cathode LED drivers and TTL input stages requiring low-true signaling |
| Full I/O buffering | Provides consistent propagation delay, noise rejection, and drive strength across all pins - simplifies timing analysis in mixed-signal systems |
| Wide VDD range (3–18 V) | Enables use in both 5 V legacy systems and higher-voltage industrial control rails without external level translation |
| TTL-load drive per output | Supports direct connection to standard LS-TTL inputs without pull-up resistors or buffer amplifiers |
Applications
| Keypad Interface for Industrial HMI | Decimal-to-BCD Conversion in Test Equipment |
|---|---|
Use Scenario: A 10-key numeric panel feeds directly into a microcontroller GPIO port via CD40147BMT to reduce pin count and eliminate software debounce complexity. IC Role / Device Role / Timing Role: Priority encoder translating mechanical keypresses into unambiguous BCD code before MCU sampling. Use Value: Reduces required MCU input pins from 10 to 4 while ensuring only the topmost pressed key is registered - critical for overlapping or bounce-prone switches. | Use Scenario: A programmable signal generator uses CD40147BMT to convert front-panel thumbwheel switch settings (0–9) into BCD for DAC address selection. IC Role / Device Role / Timing Role: Static decimal-to-BCD translator providing synchronous digital input to precision analog subsystems. Use Value: Eliminates need for firmware-based encoding and guarantees glitch-free transitions during manual adjustment - improves calibration repeatability. |
| Fault Detection in Multi-Sensor Arrays | Legacy System Upgrade Path for 74147 Designs |
Use Scenario: Ten discrete fault indicators (e.g., overtemperature, overcurrent, communication loss) feed into CD40147BMT to report highest-priority alarm condition to a central controller. IC Role / Device Role / Timing Role: Hardware-based priority resolver compressing parallel fault status into minimal bus bandwidth. Use Value: Enables immediate response to critical faults without polling delays or software overhead - meets real-time safety monitoring requirements. | Use Scenario: Replacing obsolete 74147 TTL encoders in field-deployed equipment using CD40147BMT with pin 15 grounded. IC Role / Device Role / Timing Role: Drop-in functional replacement delivering identical BCD encoding behavior with improved power efficiency and voltage flexibility. Use Value: Extends product lifecycle without PCB redesign - leverages existing layout while reducing supply current by >90% at 5 V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar priority encoding applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CD40147BE | Same core logic and timing, but in 16-pin PDIP (N) package; no MSL rating; wider body (19.1 mm) | Preferred for prototyping, through-hole assembly, or legacy board rework where SOIC footprint is unavailable | Select CD40147BE when hand-soldering, socket-based testing, or compatibility with older DIP-based layouts is required |
| 74HC147 | High-speed CMOS version; operates up to 25 MHz; requires 2–6 V supply; outputs are active-low but not TTL-load capable | Better suited for high-frequency multiplexed systems or low-voltage (3.3 V) designs where speed outweighs drive strength | Select 74HC147 when operating at ≥3.3 V with strict timing budgets, but verify external pull-ups are added for TTL interfacing |
Compared with CD40147BE and 74HC147, the CD40147BMT offers superior voltage flexibility (3–18 V), guaranteed TTL-load drive without external components, and SOIC-16 surface-mount compatibility - making it optimal for ruggedized industrial upgrades and mixed-supply embedded systems.
Availability
CD40147BMT is available at Aetrix Electronics and suitable for industrial HMI interfaces, test equipment digitization, fault-monitoring subsystems, and legacy TTL upgrade paths requiring stable component supply and long-term obsolescence mitigation.
Supply support for CD40147BMT 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 company headquartered in Dallas, Texas, delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The CD40147BMT belongs to TI's legacy CMOS logic portfolio, designed specifically for robust, low-power priority encoding in harsh-environment applications where reliability and wide supply tolerance are essential.
FAQ
What is the function of pin 15 on the CD40147BMT?
Pin 15 on the CD40147BMT serves as the Enable input and must be tied low (to VSS) to activate encoding functionality. When left floating or driven high, all four BCD outputs remain logic high (VSS), effectively disabling the device. This behavior is explicitly defined in the TI SCHS102C datasheet and distinguishes CD40147BMT from non-enabled encoders. The CD40147BMT relies on this pin for system-level control of encoding activity.
Does the CD40147BMT support 3.3 V operation?
Yes, the CD40147BMT supports 3.3 V operation within its specified supply range of 3 V to 18 V. At 3.3 V, it maintains full functionality including priority encoding, active-low BCD output generation, and TTL-load drive capability - verified in TI's characterization data. The CD40147BMT is therefore suitable for mixed-voltage systems where 3.3 V logic coexists with higher-voltage peripherals, unlike many older 5 V-only encoders.
How does the CD40147BMT handle simultaneous input assertions?
The CD40147BMT resolves simultaneous input assertions using hardwired priority logic: input 9 always overrides inputs 0–8, input 8 overrides 0–7, and so on down to input 0 as lowest priority. This deterministic behavior ensures only one BCD code is generated regardless of how many inputs are active - a feature confirmed in the functional description of the CD40147BMT datasheet and essential for reliable keypad or fault-monitoring applications.
Is the CD40147BMT pin-compatible with the 74147 TTL encoder?
No, the CD40147BMT is not pin-compatible with the 74147. While functionally similar when pin 15 is grounded, the CD40147BMT uses a 16-pin SOIC package with different pin assignments - notably, inputs occupy pins 1–10 and outputs occupy pins 11–14, whereas the 74147 uses a 16-pin DIP with distinct layout. The CD40147BMT requires PCB adaptation or an adapter board for direct substitution in 74147 footprints.
What is the maximum output sink current specification for the CD40147BMT?
The CD40147BMT output stage is rated to drive one TTL low-power Schottky (LPS) load, equivalent to sinking 0.36 mA at VOL = 0.4 V (with VDD = 5 V), as specified in the TI SCHS102C datasheet. This drive strength is sufficient for direct interfacing with standard 74LS-series inputs without external pull-ups. The CD40147BMT maintains this capability across its full 3–18 V supply range, though absolute current scales with voltage.
CD40147BMT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 4000B
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Type:
- Priority Encoder
- Circuit:
- 1 x 10:4
- Independent Circuits:
- 1
- Current - Output High, Low:
- 6.8mA, 6.8mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 3V ~ 18V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
CD40147BMT FAQ
1.How can I place an order for CD40147BMT through Aetrix?
Please submit a Request for Quotation (RFQ) for CD40147BMT 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 CD40147BMT reliable?
The price and inventory of CD40147BMT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD40147BMT is usually 5 days.
3.What payment methods are accepted for CD40147BMT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD40147BMT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD40147BMT?
CD40147BMT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD40147BMT 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 CD40147BMT?
For technical support, including CD40147BMT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD40147BMT requirements.
6.How does Aetrix verify that CD40147BMT is sourced from the original manufacturer or authorized distributors?
All CD40147BMT 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 CD40147BMT meets industry standards.
7.What is the process for return or replacement of CD40147BMT?
All CD40147BMT units undergo pre-shipment inspection (PSI). If there is an issue with CD40147BMT, 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 CD40147BMT part is unused and in its original packaging.
Return procedure for CD40147BMT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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