Overview
Description
This Automatic Liquid Dispenser reference design is for hands-free dispensing of liquids such as soap, hand sanitizer, shampoos, or hand lotions. Automatic liquid dispensers are popular in public places and private institutions, as touch-free designs eliminate bacterial transmission. The dispenser only distributes a set amount of liquid per motion activation to minimize waste. When a hand is detected near the nozzle, the MCU triggers the pump motor, and the dispenser emits liquid. The liquid is automatically dispensed without the hand touching any part of the nozzle, resulting in a more hygienic environment. When a hand comes close to the nozzle, it blocks the transfer of optics between the infrared LED and phototransistor. The MCU detects the change in the phototransistor status and then activates the motor.
This solution features the RL78/G11 low pin and internally configurable analog MCU, which operates the system clock with a medium-speed on-chip oscillator, achieving low-power consumption and a fast wake-up of 4μs. It also features the ISL9001A high-performance low-dropout linear regulator, used for power management, which can source a current of up to 300mA. This regulator helps extend battery life as it supports a wide input voltage range (2.3V to 6.5V) while featuring extremely low quiescent current.
Features
- Includes the RL78/G11 MCU.
- Dispenses a fixed amount of liquid per motion activation to minimize waste.
- Activates an LED and buzzer when hands are placed under the nozzle.
- Limits dispensing to a maximum of two seconds, even if hands remain under the nozzle.
- Blinks an LED to indicate low battery when the voltage drops below 4.8V and hands are detected.
- Dispenses 0.5 ml or 0.8 ml of liquid per motion activation (selectable).
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Videos & Training
Renesas demonstrates the Automatic Liquid Dispenser quick solution featuring the RL78/G11 microcontroller. This solution uses a built-in infrared sensor and pump mechanism to detect hands and dispense a fixed amount of liquid, such as dish soap, hand sanitizer, shampoo or hand lotion.