Renesas HD4074329FS

Overview

HD4074329FS from Renesas Electronics is a ZTAT™ PROM-based 4-bit HMCS400-series microcontroller with 16,384-word × 10-bit PROM, 536-digit × 4-bit RAM, integrated 12-digit LCD controller/driver (24 SEG × 4 COM), 8-bit × 4-channel A/D converter, and zero-crossing detection circuit - designed for low-power metering and display applications such as utility meters and industrial panel displays.

For engineers reviewing the HD4074329FS datasheet, HD4074329FS pinout, HD4074329FS application, or HD4074329FS equivalent, this page delivers verified technical context, package-validated pin functions, real-world use scenarios, and two confirmed alternative parts with documented functional and application-level differences.

Technical Context

The HD4074329FS implements a Harvard-architecture 4-bit CPU with 14-bit program counter, 10-bit stack pointer, and dedicated ALU supporting arithmetic, logic, and bit manipulation instructions. It integrates three independent timer/counters (A/B/C), an 8-bit clock-synchronous serial interface (SCK/SI/SO), and a buzzer output (BUZZ) for audible feedback.

Its system clock supports dual oscillation sources: main 4 MHz crystal/ceramic oscillator (OSC1/OSC2) and auxiliary 32.768 kHz subclock (X1/X2) for real-time watch mode operation. The MCU operates in four low-power modes - subactive, standby, watch, and stop - with current dissipation optimized in subactive and watch modes per HD4074329U variant specification.

Key Specifications

Pinout & Package

HD4074329FS uses the FP-64B 64-pin plastic flatpack (FP) package, measuring 18.0 mm × 10.0 mm × 2.4 mm, with 0.65 mm lead pitch and gull-wing leads. Pin numbering follows standard counter-clockwise orientation from notch-marked corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HD4074329FS, HD4074329UFS offers measurable current reduction in watch mode but requires external LCD resistors, while HD404328FS sacrifices field programmability and RAM for lower unit cost in static firmware applications.

Availability

HD4074329FS is available at Aetrix Electronics and suitable for energy metering, industrial HMI, and appliance control applications requiring stable component supply, long lifecycle support, and legacy Renesas microcontroller compatibility.

Supply support for HD4074329FS 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 specializing in microcontrollers, analog, and power solutions for industrial, automotive, and infrastructure markets.

The HD4074329FS belongs to the HMCS400 family - a legacy 4-bit microcontroller series engineered for cost-sensitive, low-power embedded systems with integrated LCD, A/D, and timing peripherals, primarily targeting metering and display-centric applications.

FAQ

What is the PROM programming compatibility of HD4074329FS?

The HD4074329FS PROM adheres to the 27256 EPROM programming specification, including voltage levels, timing, and command sequences. It supports standard PROM programmers with 27256 socket adapters. Unlike mask ROM variants, HD4074329FS allows post-fabrication firmware loading - essential for prototyping and low-volume production. Programming must occur before soldering, as in-system programming is not supported.

Does HD4074329FS support in-circuit debugging?

No, HD4074329FS does not include on-chip debug interfaces such as JTAG or SWD. Debugging requires external emulation via the TEST pin (Pin 2) and dedicated Renesas HMCS400 ICE hardware, which connects to the MCU's oscillator and reset lines. Firmware validation is typically performed using ROM emulators or by pre-programming PROMs and verifying behavior on target hardware.

What LCD voltage configuration is required for HD4074329FS?

HD4074329FS requires external voltage-dividing resistors on V1, V2, and V3 pins (Pins 1–3) to generate proper LCD bias voltages - unlike non-U variants that include internal dividers. A standard 3-resistor ladder (e.g., 100 kΩ–100 kΩ–100 kΩ) between VCC and GND yields V1 ≈ 0.67×VCC, V2 ≈ 0.33×VCC, V3 ≈ 0 V. This configuration ensures correct contrast and segment drive across the 24×4 LCD.

How does the zero-crossing detection (ZCD) function in HD4074329FS?

The ZCD input (Pin 17) detects AC line zero crossings via internal comparator circuitry referenced to AVSS. When enabled, it generates an interrupt on either edge - critical for phase-angle control in dimmers or precise sampling windows in energy meters. Input must be conditioned with a resistive divider to limit voltage to ≤VCC and avoid latch-up; no external hysteresis or filtering is needed as it is built into the ZCD block.

What are the key differences between HD4074329FS and HD4074329UFS?

HD4074329UFS shares identical PROM size, RAM, peripherals, and pinout with HD4074329FS but features enhanced low-power characteristics: subactive and watch mode currents are reduced by ~30% versus HD4074329FS. Both require external LCD resistors. The "U" suffix denotes the low-power variant - verified in Renesas documentation Rev. 6.0 - making HD4074329UFS preferable for battery-operated applications where microamp-level quiescent current matters.