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 photo transistor. The MCU detects the change in the photo transistor 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 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.
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- Demo board includes the RL78/G11 MCU
- Dispenser distributes a set amount of liquid per motion activation to minimize waste
- If hands are placed under the nozzle, an LED and buzzer are turned on to indicate liquid dispensing
- Even if hands remain under the nozzle, liquid dispensing has a maximum duration of 2 seconds
- When battery voltage is lower than 4.8V, an LED blinks to indicate this low power condition when hands are placed under the nozzle.
- Amount of liquid per motion activation: 0.5ml/0.8ml selectable