Renesas MCUs cut power demand in domestic/industrial sensing

January 23, 2015 // By Graham Prophet
This introduction of microcontrollers claims new levels of integration and a reduction of standby power of 30%. Renesas says its RL78/I1D MCUs offer the lowest-available power consumption when operating at 1 MHz and have a complete set of on-chip analogue peripheral functions.

RL78/I1D functions are optimised for detectors that sense minute variations in the output of sensors used to monitor for smoke, gas, and motion or vibrations. The ability to use functions such as the data transfer controller (DTC), event link controller (ELC), and data operation circuit (DOC) to perform data processing and transfer, and implement long-interval timers, all without the need for CPU intervention, helps to further reduce power consumption during intermittent system operation by approximately 30%. In the low-power operation mode, the RL78/I1D Group has an operating current level that Renesas believes is much lower than that of competing products, and it wakes up from the stop-mode state very quickly. The MCU alone can make a substantial contribution to the overall power efficiency of the system.

The RL78/I1D Group integrates general-purpose differential input operational amplifiers, a 12-bit A/D converter, and a comparator. This brings together on a single chip all the analogue peripheral functions required to interface with sensors.

Features of the RL78/I1D Group include;

- Snooze mode functions enabling data processing and transfer without CPU intervention: The data transfer controller (DTC) or event link controller (ELC) can be used to activate sensors, activate operational amplifiers to amplify sensor signals, and transfer A/D conversion results. The data operation circuit (DOC) compares the transferred A/D conversion results and threshold values to determine whether the CPU needs to be activated. These snooze mode functions operate without CPU intervention in standby mode and reduce power consumption in products such as fire detectors, gas detectors, broken glass detectors, and security systems (human sensors).

- Dynamic switching of the operation mode to match the system status: The RL78/I1D Group allows dynamic switching between low-power operation mode and high-speed operation mode to match the system status. In low-power operation mode with a power supply voltage of 1.8V ≤ VDD ≤ 3.6V and an operating frequency of 1 MHz, the operating current is only 124 μA (typ.).