Texas Instruments CD40105BF

Overview

CD40105BF from Texas Instruments is a CMOS dual 4-bit presettable synchronous binary up/down counter with asynchronous reset, housed in a 16-pin CDIP (J) package. It operates over a supply voltage range of 3V to 18V, supports independent clock and direction control per counter, and features ripple-carry output for cascading. It is used in digital timing, frequency division, and position tracking circuits where dual independent counting is required.

For engineers reviewing the CD40105BF datasheet, CD40105BF pinout, CD40105BF application, or CD40105BF equivalent, key selection considerations include its dual-counter architecture, asynchronous reset behavior, wide V_DD tolerance, ripple-carry propagation delay, and CDIP J-package thermal and hermetic suitability for military-grade or high-reliability industrial control systems.

Technical Context

The CD40105BF implements two identical, independent 4-bit synchronous binary counters sharing only power and ground. Each counter has dedicated CLOCK, UP/DOWN, PRESET ENABLE, and RESET inputs, enabling fully decoupled operation. Count direction is controlled by logic level on the UP/DOWN input prior to clock edge.

Counting is synchronous with respect to the rising edge of CLOCK; all flip-flops change state simultaneously. The ripple-carry output (RCO) transitions low when the counter reaches terminal count (0000 for down-count, 1111 for up-count) and the corresponding direction input is active - enabling precise cascade timing without external gating.

Key Specifications

Pinout & Package

CD40105BF is supplied in a 16-pin Ceramic Dual In-line Package (CDIP) with JEDEC drawing J, featuring a hermetic ceramic body and tin-lead (SnPb) terminations (A42 finish). This package provides superior moisture resistance, thermal stability, and long-term reliability in harsh environments.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual synchronous counter applications.

Compared with CD40105BF, CD40192BE requires additional components to achieve dual counting, while SN74HC192N offers higher speed but sacrifices supply flexibility, temperature range, and package robustness - making CD40105BF uniquely suited for high-integrity, multi-range, space-constrained embedded counting.

Availability

CD40105BF is available at Aetrix Electronics and suitable for industrial motion control, avionics monitoring, and legacy system upgrades requiring stable component supply, long-lifecycle assurance, and hermetic packaging performance.

Supply support for CD40105BF 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 logic solutions, with leadership in high-reliability and industrial-grade components.

The CD40105BF belongs to TI's CD4000-series CMOS logic family, designed for robust operation in extended temperature, high-noise, and mixed-voltage environments where TTL alternatives fail.

FAQ

What is the maximum operating frequency of the CD40105BF?

The CD40105BF does not specify a fixed maximum clock frequency in its datasheet; instead, it defines propagation delays - e.g., 120 ns max at 5V. This implies a practical upper limit near 8 MHz at 5V, decreasing to ~5 MHz at 10V due to increased delay. Actual system frequency depends on load capacitance, supply stability, and cascade depth. The CD40105BF's synchronous architecture avoids cumulative ripple delays, supporting reliable multi-stage operation within these bounds.

Is the CD40105BF pin-compatible with the CD40192 or CD40193?

No, the CD40105BF is not pin-compatible with CD40192 or CD40193. Those are single 4-bit up/down counters in 16-pin packages but assign different functions to pins 1–4 (outputs) and lack dedicated dual-clock and dual-reset inputs. CD40105BF dedicates pins 1–4 and 13–16 to two independent output buses, with separate clocks (Pins 7 and 10) and resets (Pins 5 and 12). Substitution would require PCB redesign.

Does the CD40105BF support asynchronous loading of preset values?

No, the CD40105BF does not support asynchronous preset loading. It features synchronous preset enable (PE) control - preset data on the parallel inputs is loaded on the next rising clock edge when PE is active. This differs from asynchronous load devices like the CD40192, which load preset values immediately upon PE assertion. The CD40105BF's synchronous behavior ensures glitch-free state transitions aligned with system clock domains.

What is the significance of the "F" suffix in CD40105BF?

The "F" suffix in CD40105BF denotes the Ceramic Dual In-line Package (CDIP) variant with JEDEC drawing J and military-grade screening (e.g., MIL-STD-883 compliance). It distinguishes this hermetically sealed, high-reliability version from plastic DIP variants (e.g., CD40105BE). The CD40105BF is rated for –55°C to +125°C operation and intended for aerospace, defense, and critical industrial applications where moisture resistance and thermal stability are mandatory.

Can the CD40105BF be used with a 3.3V supply?

Yes, the CD40105BF is fully specified to operate at 3.3V - its minimum V_DD is 3V, and all DC and AC parameters (including propagation delay and noise margin) are guaranteed across the full 3V–18V range. At 3.3V, typical propagation delay increases to ~250 ns, but logic thresholds remain valid, and output drive capability meets CMOS-compatible loads. This makes the CD40105BF suitable for mixed-voltage systems interfacing with modern 3.3V microcontrollers without level-shifting circuitry.