Proving the Business Case for the Internet of Things

Renesas and Toshiba combine features for healthcare devices and wearables

Steve Rogerson
July 14, 2015
 
Two leading Japanese chip makers – Renesas Electronics and Toshiba – are targeting the low-power wearables and healthcare market with their latest offerings.
 
Renesas has developed a microcontroller that it says provides the optimal combination of performance and low power consumption for healthcare and wearable devices. And to meet IoT requirements for low-power consumption, Toshiba has developed a flash memory process that is said to use less power than current mainstream technologies and is aimed at markets such as wearables and healthcare-related equipment.
 
The Renesas RX231 32bit microcontrollers (MCUs) are said to offer industrial and healthcare designers high performance with digital signal processing (DSP), floating point unit (FPU) and low power consumption. This means they suit applications that require high processing performance in environments with low current supply capacity, such as industrial sensors, healthcare devices, wearable devices, and building automation devices such as thermostats.
 
With industrial sensors and healthcare devices, processing can be time consuming and inefficient. Batteries for these types of systems are designed to support low current supply capacity, but during signal measurement they must handle high processing loads, such as eliminating noise from digital signals and performing floating-point calculations. As the current consumption cannot be increased, designers cannot boost the processing speed by raising the operating frequency of the CPU. The long processing durations cause increased power loss for the entire system.
 
The RX231 devices provide an optimal combination of power-efficient MCU technology and the high-performance RXv2 CPU core with DSP and FPU operation capabilities. They reduce current consumption and handle tasks involving heavy calculation loads such as digital filtering and floating-point operations considerably fast. This makes it possible to reduce the power loss for the system as a whole during processing.
 
For example, running the Renesas IIR digital filter consumes ten per cent less power and takes about half as long as was the case with earlier products. In addition, current consumption during standby is 0.8μA, approximately half the level of previous generations. With these power performances, power efficiency is approximately doubled during intermittent operation in which operating and standby states alternate. This allows extended operation on battery power.
 
The RXv2 CPU core achieves a performance benchmark score of 4.16CoreMark/MHz, 35 per cent higher than the RX200 series with the earlier RXv1 core. With operating speeds of 54MHz, and approximate increases of two to four times in DSP performance and six times in FPU performance, the MCUs can reduce the time required for high-processing load tasks such as digital filtering.
 
They achieve the current consumption of 0.8µA in standby mode while retaining the contents of both SRAM and CPU registers, and consuming only 120µA/MHz when the CPU is active with peripherals off. The RX231 can recover from standby mode in a minimum of 5µs, which makes it possible to reduce current loss during the recovery and allow the application to react quickly to external events. Applications can be executed from flash after this time, and analogue functions, such as the analogue-to-digital converter, are available for use.
 
It also supports an additional low power timer (LPT), which consumes an additional 0.4µA and allows the user to programme the device to wake up from the low power modes with a wide range of possible timings, reducing current consumption in many applications.
 
The device provides proven capacitive touch sensor capabilities equipped with the company’s second-generation capacitive touch technology.
 
With support for up to 24 touch keys for self-capacitance mode and up to 144 keys for mutual capacitance mode, the MCUs can support LED, buzzer and communications functions in more basic touch systems such as blood pressure monitors (typically nine keys), to systems with more elaborate requirements such as security keypads (19 keys) and ovens (25 keys). This touch key functionality combines high sensitivity with a high level of noise tolerance, allowing use even when the panel is wet or when the operator is wearing gloves. This makes it possible to create highly flexible user interfaces in terms of usage environment and device design.
 
For smart home and building automation, industrial networking, and remote sensor networks, advanced connectivity and the ability to support multiple interface standards are critical. The device supports emerging IoT platforms by providing enhanced communications functionality with complete USB 2.0 support, including device-host and OTG operation and full compliance to Battery Charging specification 2.0. The devices also have several connectivity peripherals, including up to seven SCI channels, SDHI support, a CAN interface with ISO 11898-1 compliance, and an IrDA interface for wireless connectivity and audio support.
 
Compliance with international safety standards is important in industrial automation, home appliance and electrical control applications. The MCUs offer hardware-based safety features for UL and IEC60730, including self-diagnostic and disconnect-detection monitoring for the on-chip A-D converter, clock frequency accuracy measurement circuit, independent watchdog timer, and built-in hardware memory test to spot anomalies in the internal RAM. For enhanced security, it provides AES encryption, a hardware-based random number generator and unique device ID that can be configured to support advanced cryptology requirements.
 
Samples are available now. Mass production is scheduled to begin in September 2015.
 
The Toshiba flash memory embedded process is based on 65nm logic process and a single-poly non-volatile memory (NVM) process based on 130nm logic and analogue power process. Applying the process to diverse applications should allow Toshiba to expand its product line-up in such areas as microcontrollers, wireless communications ICs, motor controller drivers and power supply ICs.
 
The company adopted Silicon Storage Technology’s third-generation SuperFlash cell technology, in combination with its own 65nm logic process technology. The company has also fine-tuned circuits and manufacturing processes in developing an ultra-low power consumption flash embedded logic process. Microcontrollers for consumer and industrial applications that apply the process can, claims the company, lower power consumption to approximately 60 per cent that of current mainstream technology.
 
Following the first series of microcontrollers, Toshiba plans to release sample BLE (Bluetooth Low Energy) products, the short-range wireless technology, in fiscal year 2016. The company also plans to apply the 65nm process to its wireless communications IC product family that can optimise use of low power consumption characteristics in applications such as NFC (near field communications) controllers and contactless cards.
 
In addition to low power consumption advantages, the process technology contributes to shorter development time, as application software can be written and rewritten to flash memory during development. By engineering advances in devices offering ultra-low power consumption to promote further development of specialised flash peripheral circuit technology and of logic and analogue circuit technology, Toshiba aims to meet continuing growth in demand for low-power applications.
 
The goal is to lower power consumption for entire systems, targeting 50μA/MHz operation, and to develop innovative products for the IoT. In applications where significant cost reductions are a concern, Toshiba has developed an NVM embedded process that adopts Yield Microelectronics’ single-poly MTP (multi-time programmable) cells on Toshiba’s 130nm logic process technology.
 
NVM and analogue circuits are embedded on a single chip that can incorporate multiple functions conventionally executed by a multi-chip system. This reduces the number of terminals and realises smaller packages. Applying MTP specifications for write times improves the process’ performance while limiting increased steps in mask pattern lithography to three or fewer, and even none. By using MTP to adjust output accuracy, Toshiba will expand its product line-up in fields where higher accuracy is essential, such as power management ICs.
 
Sample shipments of the 130nm-NVM and 65nm-flash are scheduled for the fourth quarter of 2015 and the second quarter of 2016, respectively.