Renesas HD4074318H

Overview

HD4074318H from Renesas Electronics is a ZTAT™ PROM-based 4-bit HMCS400-series microcontroller with 8-kword on-chip PROM, 34 I/O pins (21 high-voltage, up to 40 V), integrated 8-bit × 8-channel A/D converter, three timers (event counter, timer output, input capture), and 8-bit clock-synchronous serial interface - used in fluorescent display driver systems requiring rapid prototyping and maskless production.

For engineers reviewing the HD4074318H datasheet, HD4074318H pinout, HD4074318H application, or HD4074318H equivalent, this page delivers verified technical context, MCU-mode and PROM-mode pin mapping, real-time interrupt architecture, low-power mode behavior, and direct alternatives for legacy system maintenance and replacement design.

Technical Context

The HD4074318H implements a Harvard-architecture 4-bit CPU core with 101-instruction set, 14-bit program counter, and 10-bit stack pointer. It supports dual operating modes: MCU mode for execution (with RESET, OSC1/OSC2, AVCC/AVSS, and full peripheral enablement) and PROM mode for in-circuit programming via dedicated address/data/control pins (A0–A14, O0–O7, CE, OE).

Its memory subsystem includes 8,192 × 10-bit PROM, 384 × 4-bit RAM, and configurable zero-page subroutine area ($0000–$003F). Peripheral control is register-mapped in RAM addresses $000–$03F and $040–$3FF, with interrupt priority order fixed at RESET/STOPC (highest), INT0, INT1, Timer A, Timer B, Timer C, A/D, and Serial.

Key Specifications

Pinout & Package

HD4074318H is packaged in FP-44A - a 44-pin flat-pack ceramic package with 0.8 mm lead pitch and 16.0 × 16.0 mm body size.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HD404318H and HD4074318S, the HD4074318H uniquely combines ZTAT™ PROM programmability with the FP-44A ceramic flat-pack's thermal stability and reliability in industrial environments - making it the sole option for field-upgradable fluorescent display controllers requiring long-term component availability.

Availability

HD4074318H is available at Aetrix Electronics and suitable for industrial panel meters, appliance control panels, legacy test equipment, and energy meter front-ends requiring stable component supply across extended product lifecycles.

Supply support for HD4074318H 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 devices for industrial and automotive markets.

The HD4074318H belongs to the HMCS400-series - a family of 4-bit microcontrollers designed specifically for cost-sensitive, high-reliability applications requiring integrated display driving, analog sensing, and low-power operation in harsh environments.

FAQ

What is the PROM programming voltage required for HD4074318H?

The HD4074318H requires VPP = +21 V applied to the TEST pin during PROM programming mode, as specified in the HD404318 Series datasheet Rev. 6.0. This voltage enables internal high-voltage programming circuitry and must be supplied by a compatible PROM writer such as the DATA I/O 121B with Hitachi HS4318ESH01H socket adapter. The HD4074318H does not operate at VPP during normal MCU execution.

Does HD4074318H support in-circuit debugging?

No, the HD4074318H does not support in-circuit debugging. Its TEST pin is dedicated solely to PROM programming and must be tied to GND during normal operation. Debugging is performed externally via PROM writer verification, logic analyzer observation of I/O and timer outputs, and serial interface monitoring - consistent with ZTAT™ architecture constraints documented in the HD404318 Series datasheet.

What is the maximum clock frequency supported by HD4074318H?

The HD4074318H supports a maximum oscillator frequency of 4 MHz, yielding a 1 µs instruction cycle time. This limit applies to both ceramic resonator and crystal configurations on OSC1/OSC2, as well as external clock input on OSC1. Exceeding 4 MHz violates AC timing specifications and may cause instruction fetch errors or register corruption per Section 8 of the HD404318 Series datasheet.

How does the HD4074318H handle A/D conversion accuracy under varying AVCC conditions?

The HD4074318H specifies A/D linearity and offset error assuming AVCC = VCC ± 0.1 V. If AVCC differs from VCC, a 0.1 µF bypass capacitor must be placed between AVCC and AVSS to stabilize reference noise. Deviations beyond ±0.3 V degrade LSB accuracy beyond ±1 LSB per the HD404318 Series datasheet - making tight regulation of AVCC critical for precision sensor interfacing in the HD4074318H.

Can HD4074318H operate in Stop mode while maintaining RAM contents?

Yes, the HD4074318H retains full 384-digit RAM contents during Stop mode, as confirmed in Table 3 and Figure 11 of the HD404318 Series datasheet. In Stop mode, the oscillator halts, CPU resets, and all peripherals (timers, A/D, serial) are disabled - but RAM, I/O latch states, and port direction registers remain intact. Recovery occurs on STOPC pin rising edge, resuming execution from the instruction following STOP.