Low-power MCUs for environmental sensor modules

26th September 2013
Source: Renesas
Posted By : Nat Bowers
Low-power MCUs for environmental sensor modules

Renesas has expanded its popular RL78 Series of microcontrollers with 40 new RL78/L1C devices that integrate LCD display functions, USB functions, and 12-bit A/D converters on a single chip. The new RL78/L1C MCUs can interface to a wide range of sensors such as pressure, temperature, and proximity sensors, and are ideal for portable monitors and mobile healthcare applications, such as blood pressure and blood glucose monitoring equipment.

Comprising 40 products, the new RL78/L1C Group controls segment display type LCD panels and is available in 80- and 100-pin packages with on-chip flash memory capacities ranging from 64 to 256 kilobytes.

The use of sensor modules in manufacturing equipment and consumer healthcare devices to increase system functionality and intelligence continues to grow. This results in an increasing need to support the communication of data acquired by the manufacturing and consumer equipment so that the measurement results can be managed on host equipment and personal computers.

Furthermore, healthcare equipment such as blood pressure and glucose meters are becoming more widely used in homes, driving greater demand for devices that are easy and convenient to use at home, offer longer battery life, and are cost effective. Renesas addresses these needs with the new RL78/L1C MCUs featuring an on-chip USB function module and 12-bit A/D converter, contributing to lower system costs and reduced power consumption.

Key features of the RL78/L1C MCUs:

1) USB function module and 12-bit A/D converter integrated on a single chip contributes to reduced system costs

To reduce system costs in sensor modules and home health care equipment, the RL78/L1C on-chip LCD driver MCUs integrate a USB function module (compliant with the USB BC 1.2 specification) and a 12-bit A/D converter. Traditionally, external dedicated USB and A/D converter ICs plus an LCD MCU were used in these applications. The new MCUs not only provide an LCD controller, but also achieve USB communication and high-precision A/D conversion in a single chip. Eliminating the external dedicated special-purpose ICs allow system costs to be reduced by approximately 20 percent.

2) Reduced system power requirements achieved with the industry-leading low LCD drive current and USB operating current

The RL78/L1C MCUs take advantage of the RL78 Family's True Low Power performance. For instance, the RL78/L1C devices achieve an approximate 30 percent reduction in current drain during LCD drive operation compared to earlier Renesas 78K0R/Lx3 products, as well as 40 to 60 percent reductions in current drain compared to earlier Renesas products during USB operation. As a result, the RL78/L1C MCUs achieve industry-leading low power during LCD drive and USB operation.

Furthermore, by achieving the industry-leading low current drain of 0.62 microampere during 32kHz clock halt operation, the new MCUs significantly reduce current drain during standby modes when the LCD panel is not being used.

3) Enhanced communication functions with a USB BC 1.2-compliant USB module

Of the 40 new RL78/L1C devices, 20 include a USB function module for strengthened communication functionality. Sensor logs and measurements from healthcare equipment can be managed on host equipment or a personal computer using USB communication. Since this module conforms to USB BC 1.2 specifications, it can accept a maximum charging current of 1.5 ampere, 3x greater than modules that only support the USB 2.0 standard. This makes rapid charging possible and can reduce battery charging times significantly.

Renesas will provide a complete development environment for these products including the E1 on-chip debugging emulator, a dedicated Renesas Starter Kit, which consists of the required development environment at first adoption, and a code generation tool. The various USB drivers (communication class, HID class, and mass storage class) required to support rapid charging under the USB BC 1.2 specifications can be used in the Renesas e2 studio, and the IAR Embedded Workbench development environments, and volume production versions will be released sequentially. Renesas will also provide application notes covering such functions as software touch keys, LCD display, timer functions, and serial functions.

As a further development, Renesas plans to release 85-pin 7 × 7 mm LGA package versions starting in April 2014 to respond to needs for further system miniaturization.

RL78-L1C specification table

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