Renesas HD4074394FT

Overview

HD4074394FT from Renesas Electronics is a 4-bit ZTAT™ PROM-based microcontroller in the HMCS400 family, designed for compact embedded control with integrated A/D conversion, dual timers, and serial interface. It features 4,096-word PROM, 256-digit × 4-bit RAM, 21 I/O pins (including 5 high-current NMOS open-drain outputs), and operates from 2.7 V to 5.5 V at 1 µs instruction cycle (f_OSC = 4 MHz). It targets low-cost industrial sensor interfaces and appliance control systems requiring rapid prototyping and field-programmable firmware.

For engineers reviewing the HD4074394FT datasheet, HD4074394FT pinout, HD4074394FT application, or HD4074394FT equivalent, this page delivers verified technical context, package-specific pin functions, real-world use scenarios, and two validated alternative parts - all grounded in Renesas' official Rev. 7.0 documentation (Sept. 1999) and post-merger product continuity statements.

Technical Context

The HD4074394FT implements a Harvard-architecture 4-bit CPU core with 14-bit program counter, 10-bit stack pointer, and ALU supporting bit-manipulation instructions. Its memory map allocates $0000–$0FFF for PROM program/data, $000–$0FF for RAM (including dedicated registers for A/D, timers, serial interface, and port control), and vector-addressed interrupt handling across five sources including external edge-triggered INT0 and event counter EVNB.

It integrates an 8-bit × 3-channel successive-approximation A/D converter with dedicated Vref pin, two independent timer/counters (one with reload capability and output TOC, one with event-count input EVNB), and an 8-bit clock-synchronous serial interface (SCK/SI/SO). Oscillation support includes ceramic resonator (OSC1/OSC2) or external clock drive - no RC oscillator option, unlike mask-ROM variants.

Key Specifications

Pinout & Package

HD4074394FT is packaged in FP-30D - a 30-pin flat-pack plastic package with 0.8 mm lead pitch and 12.8 mm × 7.6 mm body size. Pin numbering follows standard top-view orientation with pin 1 at bottom-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-bit microcontroller applications.

Compared with HD4074394FT, HD404394FT trades field-programmability for lower NRE and higher volume cost efficiency, while HD4074344FT expands analog input count at the expense of Vref flexibility - both share identical FP-30D packaging and instruction-set compatibility.

Availability

HD4074394FT is available at Aetrix Electronics and suitable for industrial sensor nodes, home appliance control, smart power outlets, and LED lighting controllers requiring stable component supply and long-term obsolescence management.

Supply support for HD4074394FT 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

Renesas Electronics Corporation is a global semiconductor leader formed in 2010 through the merger of NEC Electronics and Renesas Technology, specializing in microcontrollers, analog, and power solutions for industrial and consumer markets.

The HD4074394FT belongs to the HMCS400 4-bit microcontroller family, designed specifically for cost-sensitive embedded control applications where integration of A/D, timers, and serial interface reduces system complexity without sacrificing real-time responsiveness.

FAQ

What is the maximum operating frequency supported by HD4074394FT?

The HD4074394FT supports a maximum oscillator frequency of 4 MHz, delivering a 1 µs instruction cycle time. This timing is guaranteed across the full operating voltage range (2.7 V to 5.5 V) and temperature range (–20 °C to +75 °C). External clock drive is permitted, but ceramic resonator operation is the recommended and characterized configuration per Renesas Rev. 7.0 documentation.

Does HD4074394FT include an internal voltage reference for the A/D converter?

No, HD4074394FT does not include an internal voltage reference. It requires an external Vref signal applied to pin 12 to set the full-scale range for its 8-bit × 3-channel A/D converter (AN1–AN3). This design allows users to optimize reference accuracy and noise immunity using precision external sources - a key distinction from the HD4074344FT variant, which uses an internal ladder network.

Can HD4074394FT be used in battery-powered applications?

Yes, HD4074394FT is well-suited for battery-powered applications due to its dual low-power modes: Standby (reduced current draw) and Stop (sub-µA quiescent current). Wake-up from Stop mode is triggered by a rising edge on the dedicated STOPC pin (pin 24), enabling event-driven operation that maximizes battery life in sensor or remote-control applications.

What programming tools are required for HD4074394FT PROM writing?

HD4074394FT uses ZTAT™ PROM technology compatible with standard 27256 EPROM programmers. Renesas specifies that PROM programming follows the same timing and voltage protocols as the 27256 device - requiring VPP = 12.5 V at pin 18 (TEST/VPP) during write cycles. No proprietary hardware or software is needed beyond industry-standard PROM writers supporting 27256.

Is HD4074394FT pin-compatible with HD404394FT?

Yes, HD4074394FT is fully pin-compatible with HD404394FT in the FP-30D package - sharing identical pin count, arrangement, electrical characteristics, and peripheral mapping. The only functional difference is firmware storage: HD4074394FT uses field-programmable PROM, while HD404394FT uses mask ROM. PCB designs can accommodate either part without layout changes.