Renesas M37478E8SP

Overview

M37478E8SP from Renesas Electronics is an 8-bit CMOS microcontroller in the 7477/7478 group, featuring 16 KB ROM, 384 bytes RAM, 20 programmable I/O ports (P0–P1, P4, P5), 8-channel 8-bit A/D converter, and four 8-bit timers. It operates at up to 8 MHz with 0.5 µs minimum instruction cycle and supports dual clock sources (XIN/XOUT and XCIN/XCOUT) for flexible timing control in embedded consumer and office automation systems.

For engineers reviewing the M37478E8SP datasheet, M37478E8SP pinout, M37478E8SP application, or M37478E8SP equivalent, this device is selected for cost-sensitive, low-power 8-bit control tasks requiring integrated analog input, serial communication (UART/clock-synchronized), and wake-up interrupt capability via P0 port - especially where SOP-42 packaging and 2.7–5.5 V supply flexibility are critical.

Technical Context

The M37478E8SP implements a standard 740-family CPU core with 71 machine-language instructions, stack depth of 192 levels, and memory-mapped I/O where ROM, RAM, and SFRs share a unified address space. Its interrupt system supports 13 sources (5 external, 7 internal, 1 software) with vectorized priority handling and configurable edge polarity on INT0/INT1/CNTR0/CNTR1.

It integrates dual clock generation: main oscillator (XIN/XOUT) for high-speed operation and sub-oscillator (XCIN/XCOUT) for low-power modes; the CPU mode register (00FB₁₆) selects between them. The A-D converter uses VREF as reference and supports 8 single-ended analog inputs mapped to P20–P27.

Key Specifications

Pinout & Package

Package: 42-pin shrink plastic DIP (Outline 42P4B), RoHS-compliant, operating temperature range –20 to +85°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M37478M8SP, the M37478E8SP offers field-programmable PROM for prototyping and firmware updates, while HD64F7055F delivers architectural scalability at the cost of compatibility - making M37478E8SP optimal for iterative 8-bit embedded development where pin-level continuity and toolchain simplicity are essential.

Availability

M37478E8SP is available at Aetrix Electronics and suitable for audio/video tuner control, VCR system management, office automation keypad interface, and industrial panel meter front-end applications requiring stable component supply across long-lifecycle consumer electronics programs.

Supply support for M37478E8SP 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.

The 7477/7478 group was designed for cost-effective, low-power 8-bit control in consumer and office equipment - emphasizing integrated peripherals, simple programming model, and flexible clocking to reduce BOM count and design complexity.

FAQ

What is the maximum operating frequency and corresponding supply voltage for the M37478E8SP?

The M37478E8SP supports a maximum oscillation frequency of 8 MHz, which requires a supply voltage of 4.5–5.5 V. At lower frequencies (≤2.0 MHz), it operates down to 2.7 V, enabling battery-powered operation. This dual-voltage specification allows designers to optimize power consumption versus performance based on application requirements - the M37478E8SP maintains full functionality across both ranges without configuration changes.

Does the M37478E8SP support in-system programming or field firmware updates?

Yes, the M37478E8SP features electrically writable PROM (One-Time Programmable), allowing firmware to be programmed after soldering onto the board using standard EPROM programmers. Unlike mask ROM variants, the M37478E8SP supports prototyping iterations and minor field updates - though it does not support in-circuit reprogramming like Flash-based MCUs. This makes the M37478E8SP ideal for low-volume customization where full Flash flexibility is unnecessary.

How many analog input channels does the M37478E8SP A/D converter support, and what is its resolution?

The M37478E8SP integrates an 8-bit successive-approximation A/D converter with 8 single-ended input channels (IN0–IN7), mapped directly to P20–P27. It uses VREF as the reference voltage, supporting ratiometric measurements. The converter operates synchronously with the CPU clock and completes conversions in a fixed number of cycles - enabling deterministic sampling timing critical for sensor monitoring applications using the M37478E8SP.

Can the M37478E8SP enter low-power modes, and how is wake-up implemented?

Yes, the M37478E8SP supports power-down mode via the STP instruction. Wake-up is triggered either by external interrupts (INT0/INT1) or - uniquely - by a low-level signal on any P0 pin (key-on-wake-up), provided bit 5 of the Edge Polarity Selection Register (00D4₁₆) is set. This feature allows the M37478E8SP to maintain sub-10 µA standby current while remaining responsive to user input, ideal for remote controls and portable devices.

What serial communication interfaces are available on the M37478E8SP?

The M37478E8SP provides one 8-bit serial I/O module configurable as either UART (asynchronous, using P14/RXD and P15/TXD) or clock-synchronized serial (using P14/RXD, P15/TXD, P16/SCLK, and P17/SRDY). It lacks SPI or I²C hardware, but the synchronous mode supports master/slave protocols with programmable baud rate and framing - making the M37478E8SP suitable for connecting to sensors, displays, or legacy peripherals without external level shifters or protocol converters.