Texas Instruments CD14538BMT

Overview

CD14538BMT from Texas Instruments is a dual precision monostable multivibrator IC with independent trigger inputs, reset capability, and complementary Q/Q̅ outputs per section. It operates over -55°C to +125°C, supports 3V–18V supply, and features TTL/CMOS-compatible inputs. It is used in timing control, pulse shaping, and debounce circuits for industrial instrumentation.

For engineers reviewing the CD14538BMT datasheet, CD14538BMT pinout, CD14538BMT application, or CD14538BMT equivalent, key selection criteria include its dual monostable architecture, wide V_DD range, guaranteed propagation delay (t_PLH/t_PHL ≤ 400 ns at 10V), temperature-rated SOIC package, and compatibility with legacy CD4098B/CD4538B designs.

Technical Context

The CD14538BMT implements two independent retriggerable monostable multivibrators, each with active-low A and B inputs, an active-low reset, and non-inverting/inverting outputs. Timing is set externally via R-C networks connected to each section's C_EXT and R_EXT pins.

It uses standard CMOS silicon-gate technology, ensuring low static current (I_DD ≤ 20 µA at 5V), high noise immunity (V_NIH/V_NIL ≥ 30% V_DD), and rail-to-rail output swing. The device is not internally compensated and requires external timing components for stable one-shot operation.

Key Specifications

Pinout & Package

CD14538BMT is supplied in a 16-pin SOIC (D) package, 7.5 mm wide, 2.00 mm max height, with 1.27 mm pitch, RoHS-compliant NIPDAU lead finish, and MSL Level-1 rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD4538BNSR and MC14538BD, the CD14538BMT offers TI's current production status, documented MSL-1 handling, and guaranteed long-term availability through TI's military/aerospace support program - making it the preferred choice for new designs requiring assured component continuity.

Availability

CD14538BMT is available at Aetrix Electronics and suitable for industrial motor control, avionics sensor conditioning, and test equipment timing applications requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD14538BMT 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 high-reliability components for industrial, automotive, and aerospace markets.

The CD14538BMT belongs to TI's legacy CMOS logic portfolio, designed specifically for precision timing functions in mission-critical systems where wide temperature operation and long-term manufacturability are mandatory.

FAQ

What is the maximum operating frequency of the CD14538BMT?

The CD14538BMT does not operate at a fixed clock frequency; it is a monostable multivibrator whose output pulse width is determined by external RC components. Its minimum pulse width is limited by propagation delay (≤400 ns at 10V), enabling reliable one-shot generation down to ~500 ns. Maximum usable frequency depends on external R and C values and system timing margins, not an internal oscillator.

Is the CD14538BMT pin-compatible with the CD4098B?

Yes, the CD14538BMT is pin-compatible with the CD4098B per TI documentation. Both devices share identical pin assignments for dual monostable functionality, including A/B trigger inputs, reset, Q/Q̅ outputs, and C_EXT/R_EXT terminals. This allows direct replacement in existing CD4098B layouts without PCB modification.

Does the CD14538BMT support retriggering during an active output pulse?

Yes, the CD14538BMT is fully retriggerable: a new trigger event applied to either A or B input during an active output pulse will restart the timing cycle from that instant. This behavior is inherent to its internal logic design and requires no external circuitry - enabling adaptive pulse extension in dynamic signal environments.

What is the recommended external timing capacitor value range for the CD14538BMT?

TI specifies stable operation with external timing capacitors from 100 pF to 10 µF. For pulse widths below 1 µs, ceramic capacitors ≥100 pF are recommended; for widths >100 µs, tantalum or aluminum electrolytic types may be used. Capacitor leakage must remain <1 nA to maintain accuracy across temperature.

Can the CD14538BMT operate from a 3.3V supply?

Yes, the CD14538BMT is fully specified for 3V–18V operation. At V_DD = 3.3V, it delivers guaranteed logic thresholds (V_IH ≥ 2.3V, V_IL ≤ 1.0V), output drive ≥±1.5 mA, and propagation delay ≤1.2 µs - making it compatible with modern 3.3V microcontroller I/O without level translation.