Renesas R1EX24128ASAS0A#S0

Overview

R1EX24128ASAS0A from Renesas Electronics is a 128-kbit (16,384 × 8-bit) two-wire serial EEPROM with I²C interface, 1.8–5.5 V single-supply operation, 400 kHz clock frequency, and 64-byte page write capability-used for nonvolatile parameter storage in consumer audio equipment, camcorders, and cellular phones.

For engineers reviewing the R1EX24128ASAS0A datasheet, R1EX24128ASAS0A pinout, R1EX24128ASAS0A application, or R1EX24128ASAS0A equivalent, key selection criteria include its SOP-8 package, −40°C to +85°C industrial temperature range, 5 ms write cycle time, 1,000k endurance cycles at 25°C, and hardware write protection via WP pin.

Technical Context

This device implements a standard I²C-compatible two-wire bus protocol with fixed 1010 device code and user-configurable A0–A2 address pins enabling up to eight devices on one bus. It uses CMOS process and MNOS memory technology to achieve low-power operation and high reliability.

The internal architecture includes a serial-parallel converter, X/Y decoders, sense amplifiers, and a high-voltage generator for programming. Write operations support both byte and 64-byte page modes, with automatic internal timing (t_WC = 5 ms) and acknowledge polling for completion detection.

Key Specifications

Pinout & Package

Package: 150-mil 8-pin plastic SOP (PRSP0008DF-B / FP-8DBV), lead-free, surface-mountable with standard reflow profile.

Key Features

Applications

Equivalent & Alternatives

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

Compared with R1EX24128ASAS0A, AT24C128B-PU offers faster communication and broader voltage tolerance, while M95128-DRMN6TP/K trades I²C simplicity for SPI speed and different protection methodology-choice depends on existing bus architecture and timing constraints.

Availability

R1EX24128ASAS0A is available at Aetrix Electronics and suitable for consumer audio equipment, camcorders, and cellular phone designs requiring stable component supply, long-term data retention, and industrial-temperature operation.

Supply support for R1EX24128ASAS0A 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 Japanese semiconductor manufacturer specializing in microcontrollers, analog, and power devices for automotive, industrial, and consumer markets.

The R1EX24xxx series was designed specifically for reliable, low-power nonvolatile storage in battery-operated consumer electronics-emphasizing write endurance, data retention, and I²C interoperability.

FAQ

What is the maximum I²C clock frequency supported by the R1EX24128ASAS0A?

The R1EX24128ASAS0A supports a maximum I²C clock frequency of 400 kHz. This value is specified under DC and AC operating conditions and applies across the full temperature range (−40°C to +85°C) and supply voltage range (1.8 V to 5.5 V). Exceeding this frequency may result in unreliable communication or missed acknowledgments due to internal timing constraints.

Does the R1EX24128ASAS0A require external pull-up resistors on the SDA and SCL lines?

Yes, the R1EX24128ASAS0A requires external pull-up resistors on both SDA and SCL lines because its SDA pin has an open-drain output structure and SCL is a passive input. Resistor values must be selected based on bus capacitance, supply voltage, and desired rise time-typically 2.2 kΩ to 10 kΩ for 3.3 V systems with ≤400 pF total capacitance.

How does the write protect (WP) pin function on the R1EX24128ASAS0A?

When the WP pin is driven high (VIH ≥ 0.7 × VCC), the R1EX24128ASAS0A disables all write operations-including byte and page writes-and returns a NACK after address reception. When WP is low (VIL ≤ 0.3 × VCC), full read/write access is enabled. WP status is sampled asynchronously and provides hardware-level protection independent of I²C command flow.

What is the page size and maximum number of bytes that can be written in a single R1EX24128ASAS0A page write operation?

The R1EX24128ASAS0A supports a fixed page size of 64 bytes. A single page write operation can program up to 64 consecutive bytes starting from any address aligned to a 64-byte boundary (e.g., 0x0000, 0x0040, 0x0080). Attempting to cross a page boundary causes automatic rollover within the same page, potentially overwriting earlier data in that page.

Is the R1EX24128ASAS0A compatible with standard I²C protocol implementations?

Yes, the R1EX24128ASAS0A is fully compliant with the standard I²C bus specification, including start/stop conditions, 7-bit addressing with R/W bit, 8-bit data transfers, and ACK/NACK signaling. It uses the fixed device code "1010" followed by three programmable address bits (A2–A0) and supports standard 100 kHz and 400 kHz modes without requiring custom protocol extensions.