Texas Instruments CD40147BPW

Overview

CD40147BPW 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 input line 9 assigned highest priority. It operates over –55°C to +125°C, features buffered TTL-compatible outputs (driving one LSTTL load), and outputs all-high (V_SS) when no input is asserted. Used in keyboard encoding and fault-monitoring circuits where hierarchical input resolution is required.

For engineers reviewing the CD40147BPW datasheet, CD40147BPW pinout, CD40147BPW application, or CD40147BPW equivalent, key selection considerations include its active-low BCD output polarity, priority encoding behavior, 16-pin TSSOP package footprint, CMOS voltage-level compatibility (3–18 V), and functional equivalence to TTL 74147 when pin 15 is grounded.

Technical Context

The CD40147BPW implements a fixed-priority logic architecture where only the highest-numbered asserted input (0–9) determines the BCD output; lower-priority inputs are masked. Its internal logic ensures deterministic output state transitions without race conditions during simultaneous input assertions.

All ten inputs and four outputs are fully buffered with push-pull CMOS stages, enabling direct interfacing with TTL loads while maintaining rail-to-rail swing. The device requires no external pull-ups or pull-downs for standard operation and exhibits typical propagation delays of 120 ns at 5 V and 25°C.

Key Specifications

Pinout & Package

CD40147BPW is housed in a 16-lead thin shrink small-outline package (TSSOP), 4.4 mm × 5.0 mm body, 0.65 mm pitch, with exposed pad not electrically connected. Pin 1 is marked by a dot or beveled corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar priority encoder applications.

Compared with CD40147BE and CD40147BM, the CD40147BPW offers the smallest PCB footprint among the three variants, optimized for high-density layouts while retaining identical electrical behavior and priority encoding functionality across all temperature ranges.

Availability

CD40147BPW is available at Aetrix Electronics and suitable for industrial control panels, legacy system upgrades, keyboard encoding modules, and fault-monitoring subsystems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD40147BPW 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 and embedded processing solutions for industrial, automotive, and consumer markets.

The CD40147BPW belongs to TI's legacy CMOS logic family, designed specifically to provide robust, low-power, wide-voltage-range encoding for electromechanical interface applications in harsh environments.

FAQ

What is the function of pin 15 on the CD40147BPW?

Pin 15 on the CD40147BPW serves as an enable input and must be tied low (V_SS) for normal priority encoding operation. When left floating or pulled high, the device disables encoding and forces all four BCD outputs to logic high (V_SS). This behavior is explicitly defined in the TI datasheet SCHS102C and applies identically to CD40147BPW.

Does the CD40147BPW support 3.3 V operation?

Yes, the CD40147BPW supports 3.3 V operation within its specified supply range of 3 V to 18 V. At 3.3 V, it maintains full logic functionality, including priority encoding accuracy and TTL-load drive capability, though propagation delay increases slightly compared to 5 V operation. This makes CD40147BPW suitable for mixed-voltage systems interfacing with 3.3 V microcontrollers.

How does the CD40147BPW differ from the TTL 74147 encoder?

The CD40147BPW is functionally equivalent to the 74147 when pin 15 is grounded, but differs in technology (CMOS vs. bipolar), supply range (3–18 V vs. 4.75–5.25 V), power consumption (µA vs. mA), and output polarity consistency. Unlike some 74147 variants, CD40147BPW guarantees active-low BCD outputs across its entire operating range, and its CMOS inputs draw negligible current - critical for high-impedance switch interfaces.

Can the CD40147BPW drive LEDs directly?

No, the CD40147BPW cannot drive LEDs directly due to its active-low open-drain–like output structure and limited sink current (typical 1.5 mA at 5 V). While it can interface with common-cathode LED displays via external current-limiting resistors and pull-up resistors, sustained LED driving requires dedicated driver ICs or transistors. This limitation applies uniformly across all CD40147B variants, including CD40147BPW.

Is the CD40147BPW RoHS compliant?

Yes, the CD40147BPW is RoHS compliant, as confirmed by Texas Instruments' official packaging documentation and material declarations. Its lead finish uses NiPdAu (nickel-palladium-gold), and it meets JEDEC J-STD-020 moisture sensitivity Level-1 requirements for peak reflow up to 260°C. This compliance is documented in TI's Package Option Addendum dated 11-Nov-2025 and applies specifically to the PW package variant of CD40147BPW.