NXP Semiconductors 74HC21DB,112

Overview

74HC21DB,112 from Nexperia is a dual 4-input CMOS AND gate in SSOP14 package, operating from 2.0 V to 6.0 V supply, delivering propagation delays as low as 10 ns at 5.0 V/15 pF, with ±25 mA output drive and guaranteed operation from −40 °C to +125 °C - used for combinational logic in industrial control I/O conditioning and digital signal routing.

For engineers reviewing the 74HC21DB,112 datasheet, 74HC21DB,112 pinout, 74HC21DB,112 application, or 74HC21DB,112 equivalent, key selection criteria include input clamping diode support for overvoltage-tolerant interfacing, high noise immunity (typ. 45 % of VCC), JEDEC-compliant ESD ratings (HBM >2000 V), and dual independent gate architecture enabling compact logic consolidation.

Technical Context

The 74HC21DB,112 implements two independent 4-input AND functions using standard CMOS silicon technology, with inputs featuring integrated clamp diodes that allow safe interface to signals exceeding VCC when current-limiting resistors are used. Each gate outputs a fully rail-to-rail CMOS-compatible signal with symmetrical VOH/VOL specifications across its full temperature range.

Its logic behavior follows strict Boolean AND truth tables with no internal latching or state retention; all propagation delays (tpd) and transition times (tt) are characterized under defined load (CL = 15 pF) and supply conditions (VCC = 2.0/4.5/6.0 V), and static parameters including VIH/VIL thresholds scale linearly with VCC.

Key Specifications

Pinout & Package

74HC21DB,112 uses the SOT337-1 (SSOP14) package: plastic shrink small outline, 14 leads, body width 5.3 mm, 0.65 mm lead pitch, gull-wing leads, moisture sensitivity level 1 (MSL1).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual 4-input AND gate applications.

Compared with 74HC21D,112, the 74HC21DB,112 offers 25 % smaller footprint and improved thermal dissipation in SSOP14, while SN74HC21DR trades minor timing margin for broader distributor availability - making the DB variant optimal for space-constrained industrial PCBs requiring maximum timing predictability.

Availability

74HC21DB,112 is available at Aetrix Electronics and suitable for industrial automation, sensor fusion nodes, and embedded power sequencing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74HC21DB,112 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

Nexperia is a global semiconductor expert focused on essential efficiency technologies, delivering high-performance logic, discrete, and MOSFET solutions optimized for reliability and energy efficiency.

The 74HC21 belongs to Nexperia's 74HC High-Speed CMOS Logic family, designed specifically for robust, low-power, pin-compatible replacements of legacy TTL logic in industrial, consumer, and communications equipment.

FAQ

What is the maximum clock frequency supported by the 74HC21DB,112?

The 74HC21DB,112 is a combinational logic device with no internal clock; its usable toggle rate depends on propagation delay and system loading. With tpd = 10 ns typical at 5 V/15 pF, it supports reliable operation up to ~30 MHz in cascaded configurations - verified via waveform testing per Fig. 5 in the datasheet.

Can 74HC21DB,112 inputs safely interface with 12 V signals?

No - input clamp diodes limit safe overvoltage to VCC + 0.5 V. For 12 V signals, an external series resistor (e.g., 10 kΩ) plus Schottky clamp to VCC is required. Direct 12 V connection risks permanent damage, as absolute max input voltage is VCC + 0.5 V per Table 4.

Does 74HC21DB,112 support mixed-voltage operation (e.g., 3.3 V inputs driving 5 V outputs)?

No - it is a single-supply device: all inputs and outputs reference the same VCC. VIH minimum is 3.15 V at VCC = 4.5 V, so 3.3 V inputs may not reliably register HIGH when VCC = 5 V. Use 74LVC21 or level translators for true mixed-voltage interfacing.

Are pins 3 and 11 internally connected or truly unconnected?

Pins 3 and 11 are confirmed as no-connect (n.c.) per Table 2 and functional diagrams - they are not bonded and have no internal connection. Leaving them unconnected is mandatory; tying them to VCC or GND violates the datasheet and may cause unpredictable behavior or increased leakage.