ROHM Develops Ferroelectric Memory (FeRAM) Equipped with Ultra-High Speed Serial B US

LAPIS Semiconductor (www.lapis-semi.com/kr), a member of the ROHM (www.rohm.co.kr) group, has developed a 64Kbit ferroelectric memory (hereinafter FeRAM) equipped with a serial bus, suitable for smart meters, healthcare devices, car navigation systems, etc., that require high-frequency log data acquisition and high-speed data backup in emergencies.

FeRAM, which is attracting attention as a next-generation non-volatile memory, contributes to the low-power and high-functionality of applications due to its characteristics of high-speed data rewrite, high rewrite resistance, and low power consumption compared to generally available non-volatile memory.

Realization of lowest operating voltage and operating frequency

This FeRAM product ( MR44V064B/MR45V064B) achieves the industry's highest minimum operating voltage of 1.8V, allowing FeRAM to be used with two nickel-hydrogen batteries. With two AAA rechargeable batteries, it is possible to rewrite for about 11 years (at 64Kbit per second rewrite), further contributing to the long-term operation of applications and making it usable in portable devices and IoT fields.

In addition, it supports a maximum operating frequency of up to 40MHz (SPI BUS), enabling 64Kbit data rewrite time to be executed in just 1.64msec, thereby realizing high data reliability through ultra-high-speed backup in the event of a system failure. Two types of products with different serial BUSes (I2C BUS, SPI BUS) are available, allowing for compatibility with the customer's system specifications.

Mass production of this product began in January 2016 (sample price 500 yen/unit). Front-end production is carried out at the ROHM headquarters factory (Kyoto), while back-end production is handled by ROHM Electronics Philippines. Lapis Semiconductor plans to continue developing low-power, high-performance products and expand its product lineup with various capacities and interfaces to meet customer demands.

What is the reason for developing this?

Recently, due to the trend toward lower power consumption, low-voltage operation of the entire system is required not only in automobiles and industrial equipment but also in all applications. At the same time, as the amount of data increases due to high functionality, it has become necessary to store information in memory at high speed. Lapis Semiconductor has been developing the FeRAM series since 2011 through the fusion of ROHM's ferroelectric memory manufacturing technology and Lapis Semiconductor's memory design technology.


▲ Characteristics of FeRAM

What advantages does it have?

1. Enables long-term battery operation with a minimum operating voltage of 1.8V.

By utilizing ROHM’s low-power ferroelectric process technology and securing the gate potential of the memory select transistor under low voltage, the industry’s lowest operating voltage of 1.8V has been realized. As a result, memory can be used with just two nickel-hydrogen batteries. For example, since it can operate for approximately 11 years using two AAA batteries while continuously rewriting 64Kbit (about 10 sheets of manuscript paper) of data once per second, it can be utilized in IoT fields that require long-term battery operation.


▲ Discharge characteristics of two nickel-hydrogen batteries of ROHM FeRAM and emergency data backup characteristics upon power interruption.

2. Realization of the highest level of high-speed operation

Ultra-high-speed access was achieved by reducing the selector load when selecting ferroelectric capacitors for data storage. It supports Hs-mode with an industry-leading operating frequency of 3.4 MHz via I2C. It also supports an industry-leading maximum operating frequency of 40 MHz via SPI, enhancing the high-speed data rewrite feature that is an advantage of FeRAM.

Since the 64Kbit data rewrite time is very high at just 1.64msec, data can be backed up before the power is cut off even in the event of unexpected voltage drops such as power outages, resulting in a low risk of data loss and eliminating the need to deploy components to extend the power supply in preparation for power failures. It is suitable for applications requiring high security for data preservation along with high speed.

  ■ Product Specifications Summary