Design Of Low Power Infrared Proximity Sensor XDU1486

With the popularity of the large screen products like smart phones and tablet computers, lowering power consumption of the chip has become a hot topic. In this case, infrared proximity sensor is born to detect the distance between the face and the screen, as to determine whether to turn off the screen, lower power consumption and prevent misuse. As the sensors become mature, its application has spread from the consumer electronics market to many areas. There is a broad market prospect in the study of infrared proximity sensor.This paper described some theoretical knowledge needed in the design of infrared proximity sensor and traditional photoelectric sensor design. Combined with market demand, we has achieved the design system solutions and performance indicators of XDU8614, and described the principle of the key sub-modules in detail, as well as the function and performance indicators of these modules. In order to solve the power problems and the interference problems of the commercially-available infrared proximity sensor, the design of this paper adds a current source module—IREF_NEW module. This module provides the required current and voltage to the oscillator in the sleep state and lower operating frequency, leading to reducing power of the system in the sleep state; as for the interference problem, this design adopt the optical coating to suppress the influence of the light outside of wavelength 850 nm ~ 950 nm. We use mixed analog-digital subtraction circuit controlled by the timing and take steps to filter dark current in the photodiode and the infrared noise in the environments, achieving precise detection. By taking the two steps above, the chip can be used in various portable devices and a variety of strong infrared radiation environments. The chip integrates an infrared LED driver and I2 C interface circuit, not only can easily connect with the external circuit, but also can communicate with the microprocessor, interrupt through the chip pins output simultaneously, have a programmable ability and very easy to access.The designed circuit of XDU1486 is based on the 3.3V 0.35μm CMOS(Complementary Metal Oxide Semiconductor) process. The simulations of sub-blocks and whole circuits have been completed by using cadence software, such as Hspice and Hsim. According to the simulations results, the chip power consumption current can be as low as 10μA under the sleep state. The function and performance of the whole circuit can meet all the requirements of market.