Renesas M37641F8HP

Overview

M37641F8HP from Renesas Electronics is an 8-bit single-chip microcomputer in the 740 FAMILY / 7600 SERIES, featuring 64 KB on-chip ROM, 2 KB RAM, a 16-bit timer with capture/compare, UART and serial I/O interfaces, and operation at up to 10 MHz - used in industrial control panels requiring deterministic real-time response and low-power standby.

For engineers reviewing the M37641F8HP datasheet, M37641F8HP pinout, M37641F8HP application, or M37641F8HP equivalent, key selection considerations include its mask-ROM-based firmware permanence, 5V-tolerant I/O capability, integrated frequency synthesizer for flexible clock generation, and support for key-on wake-up interrupt in battery-backed systems.

Technical Context

The M37641F8HP implements a 740-core CPU with 16-bit address space and Harvard architecture memory organization. It integrates a programmable frequency synthesizer (FSYN) capable of generating internal clocks from 100 kHz to 10 MHz using external crystal or ceramic resonator inputs, and supports both single-chip and expanded bus modes via its master CPU bus interface.

Its interrupt system includes 16 vector sources with priority encoding, and its DMAC supports three independent channels with fixed- or variable-length transfers between RAM, peripheral registers, and external memory - enabling efficient data movement without CPU intervention during UART or timer-triggered operations.

Key Specifications

Pinout & Package

Package: 64-pin plastic QFP (QP-64), 14 mm × 14 mm, 0.8 mm pitch, lead-free compliant per RoHS.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with UPD78F0503GC-GAD-AX and HD64F3687FP, the M37641F8HP offers deterministic mask-ROM execution, lower system cost without flash programming infrastructure, and optimized 5V I/O drive strength for legacy industrial backplanes - making it preferable for cost-sensitive, high-volume, field-unmodifiable control applications.

Availability

M37641F8HP is available at Aetrix Electronics and suitable for industrial HMI panels, factory floor controllers, and energy meter front-ends requiring stable component supply and long-term obsolescence management.

Supply support for M37641F8HP 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 headquartered in Tokyo, Japan, specializing in microcontrollers, analog, power, and SoC solutions for industrial, automotive, and infrastructure markets.

The 7641 Group belongs to Renesas' legacy 740-family 8-bit MCU product line, designed specifically for cost-effective, high-reliability embedded control in industrial automation, building management, and metering applications where long-lifecycle support and mask-ROM security are critical.

FAQ

What is the maximum operating frequency of the M37641F8HP?

The M37641F8HP operates at a maximum system clock frequency of 10 MHz, achieved using its integrated frequency synthesizer with an external 1–10 MHz crystal on XIN/XOUT. This frequency enables consistent 1.25 MIPS performance and sub-100 µs interrupt response time - verified in Renesas' 7641 Group User's Manual Rev.2.00. The M37641F8HP does not support overclocking beyond this specification.

Does the M37641F8HP support in-circuit debugging or programming?

No, the M37641F8HP uses mask-programmed ROM and lacks on-chip debug interfaces such as JTAG or SWD. Firmware is permanently embedded during manufacturing, and no field reprogramming capability exists. Debugging must be performed pre-production using emulator hardware compatible with the 740-family architecture. This design choice ensures firmware integrity in deployed M37641F8HP units.

What power supply voltage range is specified for the M37641F8HP?

The M37641F8HP is rated for a single 5 V ±10% supply (4.5 V to 5.5 V), as confirmed in the electrical characteristics section of the Renesas 7641 Group User's Manual. It draws typical current of 15 mA at 10 MHz and drops to <10 µA in STOP mode with key-on wake-up enabled - making it suitable for 5 V industrial rails without additional regulation. The M37641F8HP does not support 3.3 V operation.

Can the M37641F8HP generate baud rates for UART communication independently of the main clock?

Yes, the M37641F8HP uses its frequency synthesizer (FSYN) to derive dedicated clock sources for UART1 and UART2, allowing independent baud rate generation from the main system clock. Supported rates include standard values such as 9600, 19200, 38400, and 115200 bps - all achievable with ≤0.5% error using internal dividers. This capability is documented in Section 2.4 of the M37641F8HP user manual and applies directly to the M37641F8HP configuration.

Is the M37641F8HP pin-compatible with other members of the 7641 Group?

The M37641F8HP shares the same 64-pin QFP package and core pinout with other 7641 Group variants (e.g., M37641F6HP, M37641F9HP), but differences in ROM size, RAM allocation, and option byte settings affect functional compatibility. While PCB layout may be reused, firmware and initialization sequences must be validated per specific part number. Pin compatibility is confirmed in Renesas' "PIN CONFIGURATION" chapter for the M37641F8HP.