ICs enable precision battery-remaining detection.

Press Release Summary:

R2J24020F Group ICs are available in SiP configuration that features 16-bit MCU integrated with A/D converter for measuring current and voltage. Designed for lithium-ion battery packs with Smart Battery System (SBS) support, ICs are available in 3 flash memory capacities for storing MCU programs and come in compact 48-pin LQFP package. E8a Emulator on-chip debugger with single-pin interface support is available as development environment.

Original Press Release:

Renesas Technology Releases R2J24020F Group of Smart Battery IC Enabling High-Precision Battery-Remaining Detection

16-bit MCU for enhanced processing performance and highly precise voltage and current measurement

Tokyo, December 8, 2008 - Renesas Technology Corp. today announced the R2J24020F Group for lithium-ion battery packs with Smart Battery System (SBS)1 support. Sample shipments will begin on December 9, 2008, in Japan.

The newly developed R2J24020F Group of System in Package (SiP) products combine a controller MCU chip and an analog front end chip in a single package and improve on the functionality of the earlier R2J24010F Group from Renesas Technology. The control MCU is built around a high performance 16-bit CPU core and integrates a high-precision, power-efficient A/D converter for measuring current and voltage. The single-package SiP configuration provides a smaller mounting area, reduces the number of external components, and requires fewer man-hours for initial calibration,² thereby reducing the production cost of each battery pack.

Product Background

In recent years the popularity of battery-powered mobile devices such as notebook PCs has grown rapidly. The battery packs of these devices are primarily of the lithium-ion or similar types in order to achieve high energy density and extended battery life without increasing the external dimensions. In addition, accurate battery-remaining indication is a key element in improving the usefulness and flexibility of battery-powered devices. There is high demand for improved battery charge/discharge safety and more precise battery-remaining indication in such devices.

Smart Battery System is a specification that standardizes the specifications for data and communication between battery and device in order to provide detailed indication and management of the battery charge remaining, etc., in products such as notebook PCs. To implement the necessary functionality on the battery end requires an analog front end chip, for internal battery measurement and control, and a control chip such as an MCU, for communication with the device.

Renesas Technology already mass produces the widely adopted R2J24010F Group of SiP products for lithium-ion battery packs supporting the Smart Battery System standard. Each combines in a single package an 8-bit MCU chip and an analog front end battery protection control chip. The new R2J24020F Group responds to market demand for improved battery-remaining indicator accuracy with a 16-bit MCU for better performance and an A/D converter with enhanced precision.

Product Features

The main features of the R2J24020F Group are outlined below.

o MCU with R8C 16-bit CPU core for improved processing performance

The control MCU is built around the R8C 16-bit CPU core. The R8C is the same CPU core used in Renesas Technology's popular R8C Family of MCU products. It delivers powerful processing performance as well as low EMI (Electro Magnetic Interference) and high EMS (Electro Magnetic Susceptibility). The 16-bit MCU boosts processing performance, enabling faster instruction execution speed. This allows lower current consumption with shorter transition time from operating mode to low power mode for example.

o High-precision, power-efficient current integrator circuit and A/D converter

It is necessary to measure the battery's current and voltage levels to provide battery-remaining indication functionality. Earlier products from Renesas Technology used ΔΣ (delta-sigma) A/D with 14-bit resolution for the current integrator circuit and a ΔΣA/D converter with 12-bit resolution for voltage measurement. The R2J24020F Group boosts the resolution to 15/16-bit for the current integrator circuit and 13-bit for the voltage measurement A/D converter for more precise battery-remaining indication.

In addition, the improved linearity of the A/D converter reduces the number of man-hours required for initial calibration. The A/D converter benefits from several enhancements to the circuit design and other aspects that reduce power consumption to about one-tenth that of earlier Renesas Technology products.

o SiP configuration for smaller mounting area and fewer external components

The SiP configuration combines the MCU chip and analog front end chip in a single package, shrinking the mounting area by about 30% compared with using two packages (comparison with equivalent Renesas Technology products) and reducing the number of external components for a lower battery pack price overall.

o Available in three flash memory capacities

The R2J24020F Group is available with any of three on-chip flash memory capacities for storing MCU programs. This allows customers to select the memory capacity that matches the size of the software they plan to develop.

Renesas Technology can ship R2J24020F Group products either with the flash memory preprogrammed with the customer's software or blank.

The compact 48-pin LQFP package (7 mm × 7 mm) contributes to a smaller board form factor.

The E8a Emulator on-chip debugger with single-pin interface support is available as a development environment. Since only one pin is needed to connect to the debugger, all the I/O pins are available for use during debugging, allowing for efficient program development. Newly added debugging functions enable referencing and changing the contents of RAM while the developer's software is running for even more efficiency.

In response to market requirements, Renesas Technology will continue to develop and release in a timely manner more products in this category, including high-end products with enhanced A/D converter functions, versions with smaller packages, and lower-priced versions for midrange applications.


1. Smart Battery System (SBS): SBS is a battery specification for devices such as notebook PCs proposed by the Smart Battery System Implementers Forum (SBS-IF). It enables the realization of "intelligent" battery packs that can monitor their own status and respond to queries (battery type, full-charge capacity, remaining capacity, charge/discharge count, battery voltage, discharge current, etc.) from the device.

2. Initial calibration: Adjustments to ensure the accuracy of voltage and current measurement. For example, the initial battery voltage calibration of the voltage measurement function involves input of two accurate reference potential points and A/D conversion by the MCU to obtain voltage values and A/D conversion values for the two points.

Typical Applications

o Devices supporting the Smart Battery System specification: Battery packs for notebook PCs and electric power tools, etc.

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