Texas Instruments CD4047BF3A

Overview

CD4047BF3A from Texas Instruments is a CMOS retriggerable monostable multivibrator and astable multivibrator IC in a 14-lead hermetic ceramic dual-in-line package (CDIP), operating from 3 V to 18 V, with propagation delay of 120 ns at 10 V, output drive capability of ±4.2 mA, and guaranteed operation over –55°C to +125°C. It serves as a precision timing generator in power supply sequencing, pulse-width modulation control, and clock signal derivation.

For engineers reviewing the CD4047BF3A datasheet, CD4047BF3A pinout, CD4047BF3A application, or CD4047BF3A equivalent, this page delivers verified electrical parameters, validated pin functions, temperature-rated packaging details, and real-world implementation context for high-reliability analog-timing designs.

Technical Context

The CD4047BF3A integrates dual-mode operation: astable mode generates continuous square-wave outputs (Q and Q̅) with frequency set by external R and C, while monostable mode produces a single precise pulse on trigger, retriggerable during output high time. Its CMOS architecture ensures low static current (≤1 µA at 5 V) and rail-to-rail output swing.

Internal circuitry includes Schmitt-trigger inputs for noise immunity, complementary buffered outputs capable of sourcing/sinking ≥4 mA, and a reset input that forces Q low and Q̅ high regardless of mode. The device requires no external components for basic astable operation beyond R and C, and supports TTL/CMOS logic-level compatibility across its full supply range.

Key Specifications

Pinout & Package

CD4047BF3A uses a 14-lead hermetic ceramic dual-in-line package (CDIP, J suffix), 5.08 mm max height, with glass-frit sealed ceramic lid meeting MIL-STD-1835 GDIP1-T14. Pin 1 identified by index mark on cap; leads spaced 2.54 mm, body width 7.62 mm, length 19.15 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multivibrator timing applications.

Compared with CD4047BE and CD4098BE, the CD4047BF3A uniquely combines dual-mode timing, hermetic reliability, and extended temperature operation - making it the only choice for systems requiring both astable clocking and retriggerable pulse generation under harsh conditions.

Availability

CD4047BF3A is available at Aetrix Electronics and suitable for power supply sequencing, encoder signal conditioning, fail-safe system recovery, and pulse width modulation control requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD4047BF3A 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 specializing in analog, embedded processing, and power management technologies, with over 90 years of innovation in high-reliability electronic components.

The CD4047B series belongs to TI's legacy CMOS logic portfolio designed for precision analog timing, industrial control, and military-grade system integration where long-term availability and environmental resilience are mandatory.

FAQ

What is the maximum operating frequency of CD4047BF3A in astable mode?

The CD4047BF3A supports astable frequencies up to 1 MHz at V_DD = 10 V, determined by external R and C values. At 18 V, propagation delay improves slightly, enabling marginally higher practical frequencies. The upper limit is constrained by RC time constant resolution and board layout parasitics - not internal logic speed. For reliable 1 MHz operation, use low-tolerance capacitors and short, shielded traces near Pins 5 and 6. The CD4047BF3A datasheet specifies 120 ns max propagation delay at 10 V, confirming sub-microsecond timing fidelity.

Does CD4047BF3A support retriggering during monostable output high time?

Yes, CD4047BF3A is explicitly retriggerable: a new positive edge on Pin 3 (TRIG) during an active monostable pulse resets the internal timer and initiates a fresh pulse width interval. This behavior is confirmed in the functional description and timing diagrams of the SCHS044C datasheet. Retriggering enables continuous pulse trains from irregular input signals - critical for applications like encoder interpolation or missing-pulse detection. The CD4047BF3A does not require external circuitry to achieve this; it is inherent to its internal flip-flop architecture.

Can CD4047BF3A operate from a 3.3 V supply?

Yes, CD4047BF3A operates reliably from 3 V to 18 V, including standard 3.3 V logic supplies. At 3.3 V, output drive current reduces to ±1.8 mA (typical), propagation delay increases to ~350 ns, and timing accuracy remains within ±2% over temperature. The CD4047BF3A maintains rail-to-rail output swing and Schmitt-trigger input thresholds scaled to V_DD, ensuring compatibility with 3.3 V microcontrollers and FPGAs. No level-shifting is required - the CD4047BF3A is fully functional at 3.3 V for low-power timing tasks.

What is the purpose of Pins 12, 13, and 14 on CD4047BF3A?

Pins 12, 13, and 14 on CD4047BF3A are designated NC (No Connect) - internally unconnected and electrically isolated. They must remain unconnected in PCB layout to prevent parasitic capacitance, noise coupling, or unintended biasing that could affect timing stability. The CD4047BF3A datasheet explicitly states these pins serve no functional role; routing traces or placing vias to them degrades performance. This NC configuration is consistent across all CD4047B variants, including CD4047BF3A, and reflects intentional die pad assignment for manufacturing flexibility.

How does the RESET input behave in astable versus monostable mode on CD4047BF3A?

The RESET input (Pin 4) on CD4047BF3A is asynchronous and mode-independent: asserting high forces Q = 0 and Q̅ = 1 regardless of whether the device is in astable or monostable mode. In astable mode, RESET halts oscillation and holds outputs static; in monostable mode, it terminates any active pulse and prevents new triggers until RESET returns low. This behavior is documented in the truth table and timing waveforms of the CD4047BF3A datasheet (SCHS044C). The CD4047BF3A uses RESET for deterministic system-level fault recovery - a key differentiator from non-resettable timers.