NXP Semiconductors 74HCT4851D,118

Overview

74HCT4851D,118 from NXP Semiconductors is an 8-channel analog multiplexer/demultiplexer with injection-current effect control, designed for automotive and industrial signal routing. It features active-LOW enable (E), three digital select inputs (S0–S2), eight independent I/Os (Y0–Y7), and a common I/O (Z). At V_CC = 5.0 V, typical ON-resistance is 76 Ω, injection-current coupling is ≤0.27 mV at 1 mA, and propagation delay is 11.5 ns (Z↔Y_n). It operates across −40 °C to +125 °C in SO16 package.

For engineers reviewing the 74HCT4851D,118 datasheet, 74HCT4851D,118 pinout, 74HCT4851D,118 application, or 74HCT4851D,118 equivalent, this page delivers verified functional behavior, validated pin-level circuit roles, confirmed automotive-grade injection-current immunity, and real-world selection guidance for analog signal switching in harsh-voltage environments.

Technical Context

The 74HCT4851D,118 implements a 1-of-8 decoder driving eight independently controlled analog switches, each with dedicated injection-current control circuitry. Its CMOS-TTL compatible input thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V at V_CC = 4.5–5.5 V) ensure robust interfacing with legacy logic systems.

When E is LOW, one Y_n–Z path is enabled with low ON-resistance and matched R_ON (≤8 Ω mismatch at 4.5 V); when E is HIGH, all channels enter high-impedance OFF-state with leakage < ±0.1 µA per channel. Disabled channels tolerate signals up to V_CC + 0.5 V without cross-coupling into the active path.

Key Specifications

Pinout & Package

74HCT4851D,118 uses SO16 (SOT109-1) package: plastic small outline, 16 leads, 3.9 mm body width, gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar analog multiplexer applications.

Compared with 74HC4851D,118 and ADG708BRUZ, the 74HCT4851D,118 uniquely balances TTL compatibility, automotive-grade injection-current tolerance, and SO16 footprint-making it optimal for cost-sensitive, high-reliability 5 V systems where transient robustness outweighs ultra-low R_ON requirements.

Availability

74HCT4851D,118 is available at Aetrix Electronics and suitable for automotive engine control units, industrial programmable logic controllers, and medical diagnostic equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74HCT4851D,118 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The 74HCT4851D,118 belongs to NXP's 74HCT logic family, engineered specifically for robust analog signal switching in electrically noisy environments where voltage transients exceed supply rails-targeting automotive and industrial control systems.

FAQ

What is the maximum allowable voltage on Y_n or Z pins when the channel is disabled?

The 74HCT4851D,118 allows disabled analog inputs to tolerate voltages up to V_CC + 0.5 V without affecting the enabled channel's output, per Table 4 limiting values. This injection-current immunity eliminates external clamping components in automotive applications where battery transients reach 16 V while V_CC remains at 5 V. The 74HCT4851D,118 achieves this via integrated injection-current control circuitry on each switch.

Does the 74HCT4851D,118 support bidirectional analog signal flow?

Yes, the 74HCT4851D,118 supports fully bidirectional analog signal routing between any Y_n pin and the common Z pin. Its CMOS transmission-gate architecture ensures symmetrical R_ON, capacitance, and leakage in both directions. This enables flexible use cases such as sharing a single ADC input across eight sensors (Z → Y_n) or distributing one DAC output to eight destinations (Y_n → Z). The 74HCT4851D,118 maintains < 8 Ω R_ON mismatch between channels at 4.5 V, ensuring consistent gain across all paths.

How does the enable input (E) interact with the select lines (S0–S2)?

The E pin on the 74HCT4851D,118 acts as a global master control: when E is HIGH, all eight analog switches are forced into high-impedance OFF-state regardless of S0–S2 states. Only when E is LOW does the 3-bit binary code on S0–S2 determine which Y_n–Z path is activated. This priority logic prevents unintended channel activation during power-up or reset sequences. The 74HCT4851D,118 specifies t_en ≤ 35 ns and t_dis ≤ 100 ns at V_CC = 4.5 V, enabling precise timing control in synchronous data acquisition systems.

What is the typical ON-resistance variation across temperature for the 74HCT4851D,118?

At V_CC = 4.5 V and I_SW ≤ 2 mA, the 74HCT4851D,118 exhibits R_ON(peak) of 76 Ω (typ) at 25 °C, rising to 270 Ω (max) over −40 °C to +125 °C per Table 6. Channel-to-channel R_ON mismatch remains ≤16 Ω across this range, ensuring predictable signal attenuation in multi-channel systems. This behavior is critical for applications like thermocouple cold-junction compensation where resistance drift directly impacts measurement accuracy. The 74HCT4851D,118's specified R_ON profile enables designers to calibrate out temperature-induced gain errors.

Can the 74HCT4851D,118 be used with 3.3 V logic control signals?

No-the 74HCT4851D,118 requires V_CC = 4.5–5.5 V and has TTL-compatible input thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V), but its control inputs (S0–S2, E) are not guaranteed to operate correctly with 3.3 V logic levels when V_CC = 5 V. For reliable 3.3 V control, use the 74HC4851D,118 variant instead, which has CMOS thresholds referenced to V_CC. The 74HCT4851D,118 is optimized for direct interface with 5 V microcontrollers and legacy TTL systems; mixing 3.3 V logic risks marginal switching and increased static power consumption.