Renesas HD4074818H

Overview

HD4074818 from Renesas Electronics is a 4-bit single-chip microcomputer with 8192-word × 10-bit PROM, 1184-digit × 4-bit RAM, LCD controller/driver (32 segments × 4 commons), voltage comparator (2 channels), and 30 programmable I/O pins-including 10 high-current outputs (15 mA max). It operates at 4.0 V to 5.5 V and supports ZTAT™ rapid prototyping for embedded instrumentation.

For engineers reviewing the HD4074818 datasheet, HD4074818 pinout, HD4074818 application, or HD4074818 equivalent, this device is selected for low-power, integrated-display MCU designs requiring on-chip watch oscillator (32.768 kHz), serial interface, and interrupt-driven real-time control in space-constrained consumer and industrial modules.

Technical Context

The HD4074818 implements the HMCS400 architecture with a 1 µs instruction cycle at 4 MHz, supporting subroutine nesting up to 16 levels and six interrupt sources-two external (INT0/INT1) and four internal (timers A/B/C, serial, timer C). Its internal oscillator accepts ceramic or crystal inputs on OSC1/OSC2, while dedicated X1/X2 pins drive a 32.768-kHz watch crystal.

It integrates an LCD driver with internal resistors and fixed bias (V1–V3), eliminating external components for 32×4 segment displays. The voltage comparator uses COMP0/COMP1 analog inputs referenced to VCref, and the clock-synchronous 8-bit serial interface multiplexes SCK/SI/SO onto R00–R02 pins.

Key Specifications

Pinout & Package

HD4074818 is housed in an 80-pin plastic flat package (FP-80A), compatible with FP-80B and TFP-80 footprints. Pin functions are fully defined per Renesas HD404818 Series Rev. 2.0 (Sept. 1998).

Key Features

Applications

Equivalent & Alternatives

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

Compared with HD404818H and HD40L4818H, the HD4074818 uniquely combines field-programmable PROM, 4 MHz operation, and full-feature integration-making it the only choice for iterative design, rapid qualification, and mixed-voltage system integration without sacrificing real-time responsiveness.

Availability

HD4074818 is available at Aetrix Electronics and suitable for electronic energy meters, portable medical monitors, industrial panel meters, and smart appliance control boards requiring stable component supply across multi-year production cycles.

Supply support for HD4074818 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 systems.

The HD4074818 belongs to the HMCS400 family of 4-bit microcomputers designed specifically for cost-sensitive, display-integrated embedded applications where low power, high I/O density, and rapid firmware turnaround are essential.

FAQ

What is the maximum operating frequency of the HD4074818?

The HD4074818 operates at a maximum clock frequency of 4 MHz, delivering a 1 µs instruction cycle time. This timing is confirmed in the HD404818 Series datasheet Rev. 2.0 (Sept. 1998), Section "Features". The internal oscillator supports ceramic resonators, crystals, or external clock sources on OSC1/OSC2, and the HD4074818 must not be operated above 4 MHz to ensure functional reliability and timing compliance.

Does the HD4074818 support in-system programming?

No, the HD4074818 does not support in-system programming. It is a ZTAT™ PROM-based microcontroller programmed prior to mounting using standard PROM programmers. Firmware updates require physical replacement of the HD4074818 device. This is explicitly stated in the "Features" section of the HD404818 Series datasheet, which defines ZTAT™ as Zero Turn Around Time for mask/PROM variants-not field-reprogrammable flash.

How many LCD segments can the HD4074818 drive, and what bias configuration is used?

The HD4074818 drives up to 32 segments and 4 commons (32×4), using static or multiplexed LCD bias generated internally via V1, V2, and V3 pins. No external bias resistors or voltage dividers are needed-the datasheet specifies that VCC ≥ V1 ≥ V2 ≥ V3 ≥ GND, and these pins must remain unconnected to external circuitry. This configuration is validated in the "LCD Driver/Controller" section of the HD404818 Series documentation.

What are the power supply requirements for the HD4074818?

The HD4074818 requires a single supply of 4.0 V to 5.5 V, as specified in the "Ordering Information" table and "Features" section of the HD404818 Series datasheet. It is incompatible with 3.3 V or lower supplies. The device draws current dependent on mode: active mode consumes typical 3.5 mA at 4 MHz, while Watch mode drops to 10 µA. GND must be connected to system ground; floating or improperly decoupled VCC causes reset instability.

Can the HD4074818's voltage comparator operate independently of the CPU core?

Yes, the HD4074818's two-channel voltage comparator (COMP0/COMP1 referenced to VCref) operates autonomously and can generate interrupts (INT0/INT1) without CPU intervention. The comparator output feeds directly into the interrupt controller, enabling wake-up from Stop or Watch mode upon threshold crossing. This behavior is documented in the "Voltage Comparator" and "Interrupts" sections of the HD404818 Series datasheet Rev. 2.0.