Renesas – RL78 Family – Bringing Ultra-Low-Power to your application

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The extensive family of Renesas RL78 microcontrollers consists of both general-purpose devices and application-specific MCUs. These increasingly popular MCUs make ultra-low-power applications possible by giving system designers advanced power-saving features and high-performance operation.

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The expanding RL78 family has solutions geared to a wide variety of your design needs

RL78’s Low-power Modes Maximize Battery Life

    • Three low-power modes maximize battery life by either putting on-chip functions such as the CPU, clock and peripherals in standby or by turning them off when they aren’t being used.

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Run mode

  • In Run mode, RL78 devices offer substantial savings in current consumed when compared to competitors.

Halt mode

  • Halt mode disables CPU operation, saving as much as 80% of total MCU current, while allowing a fast CPU wake-up time.

Stop mode

  • Stop mode achieves the lowest RL78 power consumption; it disables the CPU and on-chip functions that run on the CPU clock.

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Snooze mode

  • Some peripherals (ADC, UART and SPI) remain operational in Standby modes.
  • MCU transits from Stop mode to Snooze mode by timer trigger or serial data reception.
  • MCU wakes up only when acquired data matches the condition. If not, go back to Stop mode without CPU intervention.
  • Power savings up to 76% can be obtained; e.g., the ADC consumes 1.2mA in Snooze mode vs. 5.1mA in 32MHz Run mode.

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Wide operating range without sacrificing efficiency

  • RL78 MCUs have widest operating voltage in their class: 1.6V to 5.5V.
  • Built-in voltage regulator allows RL78-based systems to operate from a 5.0V with the same power consumption over the voltage range.

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Peripheral selection
RL78 MCUs have versatile power-down modes and main and subsystem (32kHz) clock options.

  • Peripheral functions available in Standby mode consume miniscule current:
    – 12-bit interval timer (0.02μA)
    – RTC (0.02μA)
    – WDT (0.02μA)
    – 15kHz on-chip oscillator (0.20μA)
    – 32 kHz oscillator (0.24μA)
    – LVD (0.08μA)
  • RAM data is retained in all MCU modes.
  • ADC, UART and SPI can be active in Snooze mode.
  • In Halt mode, system can wait for ADC end or serial transfer end, followed by a quick (0.3 μs) wake-up.

RunHaltSnoozeSub-HaltStop w/RTCStop
CPU
Peripherals (Main system clock)■ ADC, UART/SPI
Peripherals (32kHz clock)
RTC + 32kHz oscillator
RAM retention
12-bit interval timer (Optional peripheral, 0.02μA)
LVD (Optional peripheral, 0.08μA)
WDT + 15kHz oscillator (Optional peripheral, 0.22μA)
Power consumption w/o peripherals and optional peripherals unless otherwise specified4.6mA (32MHz) 2.1mA (32MHz)1 1.2mA (8MHz)0.54mA (32MHz) 0.26 mA (8MHz)1.2mA (32MHz, ADC) 0.7mA (32MHz, UART/SPI)0.49μA0.49μA0.23μA
Wake-up time 20.3μsec (32MHz) 1.2μsec (8MHz)5μsec122μsec18μsec18μsec

Notes 1: NOP Instruction 2: Min. time All the power consumptions listed above are typical value examples of RL78/G13 (64KB)

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