STMicroelectronics HCF4021M013TR

Overview

HCF4021M013TR from STMicroelectronics is an 8-stage asynchronous parallel-input/synchronous serial-in/serial-out static shift register in SO-16 package, operating up to 12 MHz (typ.) at 10 V supply, featuring individual parallel "jam" inputs per stage, buffered Q6/Q7/Q8 outputs, and dual-mode control via PARALLEL/SERIAL pin for automotive and industrial timing-critical data latching.

For engineers reviewing the HCF4021M013TR datasheet, HCF4021M013TR pinout, HCF4021M013TR application, or HCF4021M013TR equivalent, this device supports synchronous serial shifting and asynchronous parallel loading in mixed-signal control systems where supply voltage flexibility (3–20 V), wide temperature range (–55 °C to +125 °C), and low input leakage (≤100 nA at 18 V) are critical selection criteria.

Technical Context

The HCF4021 implements eight D-type master-slave flip-flops with independent parallel load capability and shared clock; parallel entry is asynchronous but edge-triggered on CLOCK when PARALLEL/SERIAL = HIGH, while serial entry is fully synchronous on positive clock edge when PARALLEL/SERIAL = LOW. Internal stage clock forcing enables reliable asynchronous jamming without external strobe timing.

It supports cascaded register expansion via Q8-to-SERIAL IN chaining, features three buffered outputs (Q6, Q7, Q8), and maintains full static operation across 3–20 V supply - enabling direct interface with TTL, CMOS, and mixed-voltage logic families without level-shifting.

Key Specifications

Pinout & Package

Package: SO-16 (Small Outline, 16-pin, ECOPACK® compliant, tape-and-reel packaging).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit parallel-load/serial-shift register applications.

Compared with CD4021BE and 74HC165, the HCF4021M013TR uniquely combines automotive-grade temperature range, integrated Q6/Q7 outputs, and true asynchronous parallel load - making it optimal for deterministic, multi-point sensing in harsh environments where pin efficiency and reliability outweigh raw speed.

Availability

HCF4021M013TR is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC I/O expansion, legacy computer peripheral interfaces, and consumer appliance control panels requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for HCF4021M013TR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The HCF4021 belongs to ST's legacy HCMOS logic family, engineered for robust operation in high-noise, wide-temperature industrial and automotive subsystems where static operation, supply flexibility, and long-term parametric stability are prioritized over ultra-high speed.

FAQ

What is the minimum clock pulse width required for reliable operation at 15 V supply?

At VDD = 15 V, the minimum clock pulse width (t_W) is 25 ns (max), per Table 7. This ensures sufficient setup/hold margin for internal master-slave latching. For robust design, maintain ≥50 ns pulse width to accommodate PCB trace skew and driver rise/fall time degradation across temperature.

Can HCF4021M013TR operate reliably at 3.3 V supply?

Yes - the device is specified down to 3 V supply per Table 5. At 3.3 V, propagation delay increases to ~500 ns (extrapolated from 5 V data), and output drive weakens (~0.5 mA IOH/IOL), but logic thresholds remain valid. Use with 3.3 V CMOS-compatible loads only; avoid interfacing with 5 V TTL without level translation.

How does the PARALLEL/SERIAL control pin affect timing during mode switching?

When P/S transitions from LOW to HIGH, parallel load becomes active on the next rising clock edge - no additional setup time is required beyond the standard t_setup(PI to P/S) of 10 ns (min) at 5 V. The internal clock forcing mechanism ensures atomic register update regardless of P/S transition timing relative to clock.

Is there a recommended decoupling strategy for SO-16 layout?

Place a 100 nF X7R ceramic capacitor between VDD (pin 16) and VSS (pin 8), located ≤2 mm from the package. Add a 1 µF bulk capacitor per 3–5 devices on the same supply rail. Route VDD/VSS traces with ≥0.3 mm width and avoid splitting ground planes beneath the IC to minimize noise coupling into the sensitive parallel input nodes.