Rohm presents a new, very compact 2.0 × 1.0 mm proximity sensor with the type designation RPR-0720. It is intended for applications in attachment/detachment sensing configurations with proximity detection. This enables further miniaturization and extension of battery life of earphones in conjunction with wireless mobile systems in the IoT area, also in industrial applications.
The RPR-0720 module is part of Rohm's product range of proximity sensors with light emitters and receivers in one housing. It integrates a VCSEL (Vertical cavitiy surface emitting laser) as a light emitter with higher (conical) directional selection than LEDs and a suitable sensor IC. Its compact design results from the use of in-house chips, which reduces the space requirement by around 78 % compared to conventional designs. The wide input voltage range (2.7 to 4.5 V) of the VCSEL chip used eliminates the otherwise necessary voltage booster (with power supply, three capacitors and inductor) when using a Li-ion battery, which contributes to the smaller dimensions of the module.
Current application examples: using light reflection to determine the connected or disconnected status (attachment/detachment) of earphones, smart watches, games consoles, etc., displaying the paper feed in printers, shredders and other office equipment. Similar applications can be found in e-cigarette cartridges, smartphones and laptops. Rohm offers a suitable evaluation board for the RPR-0720 Proximity Sensor (RPR-0720-EVK).
Article image legend: rohm VCSEL proximity sensor
Description of the blocks:
- Near PD: Photodiode close to the VCSEL.
- Far PD: Photodiode away from VCSEL.
- ADC: AD converter for obtaining digital data
- ADC controller + I2C interface + INT interface: ADC control logic and interface logic
- OSC: Oscillator for the clock of the internal logic
- POR: Power ON Reset. All registers are reset after VCC is switched on
- VCSELDriver: Constant current driver for VCSEL
