Texas Instruments CD14538BF

Overview

CD14538BF from Texas Instruments is a dual precision monostable multivibrator IC with independent reset and trigger inputs per section, 100% tested for propagation delay (t_PLH/t_PHL ≤ 400 ns at V_DD = 10 V), operating across -55°C to +125°C, and housed in a 16-lead ceramic dual-in-line package (CDIP). It serves as a timing element in pulse shaping, debouncing, and delay generation circuits for aerospace and industrial control systems.

For engineers reviewing the CD14538BF datasheet, CD14538BF pinout, CD14538BF application, or CD14538BF equivalent, this page delivers verified functional identity, validated pin assignments, confirmed temperature range and propagation delay specs, and two technically documented alternative options for legacy-compatible timing designs.

Technical Context

The CD14538BF implements two independent retriggerable monostable multivibrators, each with separate A (negative-edge trigger) and B (positive-edge trigger) inputs, active-low reset (R̅), and complementary Q/Q̅ outputs. Its CMOS architecture ensures low static current (I_DD ≤ 20 µA at V_DD = 5 V) and high noise immunity (V_NIH/V_NIL ≥ 45% of V_DD).

Timing is set externally via R-C networks connected to each section's C_EXT and R_EXT pins, supporting adjustable output pulse widths from microseconds to seconds. The device is fully compatible with TTL and CMOS logic families and meets MIL-PRF-38535 Class B requirements for hermetic packaging.

Key Specifications

Pinout & Package

CD14538BF is supplied in a 16-lead hermetic ceramic dual-in-line package (CDIP, J package), measuring 20.32 mm × 7.62 mm × 4.57 mm (0.800″ × 0.300″ × 0.180″), with SNPB lead finish and no moisture sensitivity rating (N/A for Pkg Type).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD4538B and MC14538, the CD14538BF offers superior propagation delay consistency, TI's extended lifecycle support for military-grade CDIP, and documented interchangeability per Harris/TI documentation - making it the preferred choice for new high-reliability designs requiring traceable hermetic timing.

Availability

CD14538BF is available at Aetrix Electronics and suitable for aerospace control systems, radiation-hardened instrumentation, and industrial safety interlocks requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD14538BF 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 specializing in analog, embedded processing, and high-reliability components for industrial, automotive, and aerospace markets.

The CD14538BF belongs to TI's legacy CMOS logic family designed for military and space applications requiring hermetic packaging, wide temperature operation, and long-term obsolescence management.

FAQ

What is the maximum operating temperature for CD14538BF?

The CD14538BF is rated for continuous operation from -55°C to +125°C. This specification is validated per MIL-PRF-38535 Class B screening and applies to the CDIP (J) package variant. The hermetic ceramic construction ensures parameter stability across this full range, with propagation delay variation held within datasheet limits. CD14538BF performance remains compliant under thermal cycling and steady-state extremes typical of avionics and downhole tool environments.

Is CD14538BF pin-compatible with CD4538B?

Yes, CD14538BF is pin-compatible with CD4538B, as confirmed in the TI datasheet SCHS093C which states "The CD14538B types are...pin-compatible with the CD4538B." All 16-pin assignments-including dual A/B trigger inputs, R̅ reset, Q/Q̅ outputs, C_EXT/R_EXT, V_DD, and GND-are identical. However, CD14538BF offers improved propagation delay (≤400 ns vs. ≤600 ns) and is supported for new designs, whereas CD4538B is not recommended for new applications.

Does CD14538BF support retriggerable operation?

Yes, CD14538BF supports fully retriggerable operation on both monostable sections. When an input trigger (A or B) occurs during an active output pulse, the timer resets and begins a new timing cycle from that instant. This behavior is inherent to the internal architecture and is explicitly documented in the functional description of the CD14538BF datasheet. Retriggerability ensures reliable pulse generation even under burst-mode or noisy input conditions.

What package type does CD14538BF use?

CD14538BF uses a 16-lead ceramic dual-in-line package (CDIP, J package), designated by the "F" suffix per TI's packaging nomenclature. This hermetically sealed package features SNPB (tin-lead) lead finish, zero moisture sensitivity rating (N/A for Pkg Type), and is screened to MIL-PRF-38535 Class B. Dimensions are 20.32 mm × 7.62 mm × 4.57 mm with 2.54 mm lead pitch.

Can CD14538BF replace MC14538 in existing designs?

Yes, CD14538BF can replace MC14538 in existing designs, as the TI datasheet explicitly states "The CD14538B is interchangeable with type MC14538." Both devices share identical pinout, electrical specifications, timing behavior, and temperature range. No PCB or schematic changes are required. CD14538BF offers the same functionality with TI's manufacturing traceability and extended support for high-reliability applications.