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 possible ultra-low-power applications by giving system designers advanced power-saving features and high-performance operation.

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 either by 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.

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Power Consumption vs. Competition Current consumed (μA/MHz)

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

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Power Consumption vs. Competition Current consumed (32.768kHz, RTC + LVD)

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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Power Consumption vs. Competition Current consumed (WDT + LVD)

Notes: 1: At 32 MHz (NOP instructions) 2: 0.49 μA (32.786 kHz and RTC only) 3: 0.23 μA (all stopped, RAM retained)

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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

Notes1: NOP Instruction 2: Min. time All the power consumptions listed above are typical value examples of RL78/G13 (64KB)

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Get your RL78/L12 Kit today!
Order Part Number: YRPBRL78L12

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