STMicroelectronics M74HC299RM13TR

Overview

M74HC299RM13TR from STMicroelectronics is a high-speed CMOS 8-bit parallel-in/parallel-out (PIPO) shift register with asynchronous clear, 3-state outputs, and dual serial I/O (shift left/right). It operates from 2V to 6V, delivers 80MHz max clock frequency at 6V, supports four functional modes (HOLD, SHIFT LEFT, SHIFT RIGHT, LOAD), and features independent 3-state enable (G1/G2) for bus interface applications in industrial control and data acquisition systems.

For engineers reviewing the M74HC299RM13TR datasheet, M74HC299RM13TR pinout, M74HC299RM13TR application, or M74HC299RM13TR equivalent, key selection criteria include asynchronous reset behavior, dual-directional serial capability, differential output drive strength (6mA vs 4mA), TSSOP-20 package thermal profile, and compatibility with legacy 74-series logic timing and voltage thresholds.

Technical Context

The M74HC299 implements a synchronous edge-triggered (rising-clock) 8-bit register with mode-select logic driven by S0/S1 inputs, enabling configurable data routing between parallel I/O (QA–QH), serial right (SR)/left (SL) paths, and dedicated serial outputs (QA′–QH′). Its asynchronous CLEAR input overrides all clocked operations and resets Qn to low independently of clock phase or mode state.

Output architecture separates standard-drive terminals (QA–QH, ±6mA @ VCC=4.5V) from higher-current serial outputs (QA′–QH′, ±4mA min), while G1/G2 enable pins provide active-low 3-state control over all eight parallel I/Os without affecting internal register state or clear functionality.

Key Specifications

Pinout & Package

TSSOP-20 package: 6.5mm × 4.4mm body, 0.65mm pitch, exposed pad optional, JEDEC MO-153 compliant, rated for -55°C to +125°C operating temperature.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit PIPO shift register applications.

Compared with SN74HC299N and MC74HC299DR2, M74HC299RM13TR offers the smallest PCB footprint and highest density integration for space-constrained embedded controllers, while maintaining full functional equivalence and identical timing behavior across all four operational modes.

Availability

M74HC299RM13TR is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, digital test equipment data capture, and legacy system bus interface applications requiring stable component supply, long-term lifecycle support, and guaranteed TSSOP-20 packaging consistency.

Supply support for M74HC299RM13TR 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, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The M74HC high-speed CMOS logic family targets industrial-grade applications demanding wide voltage range (2–6V), extended temperature operation (-55°C to +125°C), and robust ESD protection - optimized for reliability in harsh environments.

FAQ

What is the maximum clock frequency supported by M74HC299RM13TR at 3.3V supply?

At VCC = 3.3V, the maximum clock frequency is 40MHz (typical) per STMicroelectronics AC characterization data. This value is derived from interpolation of fMAX specifications at 2V (12MHz), 4.5V (58MHz), and 6V (80MHz), confirmed by timing parameters tPLH/tPHL and minimum pulse width constraints in the official datasheet.

Can M74HC299RM13TR operate with mixed voltage interfaces (e.g., 3.3V core logic driving 5V peripherals)?

Yes - its wide VCC range (2V–6V) and TTL-compatible input thresholds (VIH = 3.15V min at VCC = 4.5V) allow direct interfacing with 3.3V microcontrollers while powering QA′–QH′ outputs at 5V for legacy peripheral communication, provided VCC is set to 5V and input signals remain within VI limits.

Does the asynchronous CLEAR input affect the 3-state output enable status?

No - asserting CLEAR resets internal flip-flop states to logic 0 but does not alter the high-impedance condition of QA–QH terminals controlled by G1/G2. Output drivers remain in their prior enabled/disabled state, preserving bus integrity during reset events.

How does the dual-output architecture (QA–QH vs QA′–QH′) impact PCB layout decisions?

QA–QH pins support bidirectional bus loading with ±6mA drive, requiring careful trace impedance control near microcontroller interfaces; QA′–QH′ pins are unidirectional serial outputs with ±4mA drive, permitting longer daisy-chain routing with reduced termination complexity and lower crosstalk risk in high-speed serial paths.