The proximity function offers plug and play detection to mm without front glass thus eliminating the need for factory calibration of the end equipment or sub-assembly. The proximity detection feature operates well from bright sunlight to dark rooms. The wide dynamic range also allows for operation in short distance detection behind dark glass such as a cell phone. In addition, an internal state machine provides the ability to put the device into a low power mode in between ALS and proximity measurements providing very low average power consumption. The ALS provides a photopic response to light intensity in very low light condition or behind a dark faceplate.
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The proximity function offers plug and play detection to mm without front glass thus eliminating the need for factory calibration of the end equipment or sub-assembly. The proximity detection feature operates well from bright sunlight to dark rooms. The wide dynamic range also allows for operation in short distance detection behind dark glass such as a cell phone. In addition, an internal state machine provides the ability to put the device into a low power mode in between ALS and proximity measurements providing very low average power consumption.
The ALS provides a photopic response to light intensity in very low light condition or behind a dark faceplate. Display panel and keyboard backlighting can account for up to 30 to 40 percent of total platform power. The proximity function is targeted specifically towards near field proximity applications. In cell phones, the proximity detection can detect when the user positions the phone close to their ear. The device is fast enough to provide proximity information at a high repetition rate needed when answering a phone call.
The addition of the micro-optics lenses within the module, provide highly efficient transmission and reception of infrared energy which lowers overall power dissipation.
A Typical — Programmable from 2. Sleep Mode Power - 2. A Typical? Small Package L3. Each device combines one Ch0 photodiode visible plus infrared and one Ch1 infrared-responding IR photodiode. Two integrating ADCs simultaneously convert the amplified photodiode currents to a digital value providing up to bits of resolution.
Upon completion of the conversion cycle, the conversion result is transferred to the Ch0 and CH1 data registers. This digital output can be read by a microprocessor where the illuminance ambient light level in Lux is derived using an empirical formula to approximate the human eye response.
Communication to the device is accomplished through a fast up to kHz , two-wire I2C serial bus for easy connection to a microcontroller or embedded controller. When interrupts are enabled and a pre-set value is exceeded, the interrupt pin is asserted and remains asserted until cleared by the controlling firmware. The interrupt feature simplifies and improves system efficiency by eliminating the need to poll a sensor for a light intensity or proximity value. An interrupt is generated when the value of an ALS or proximity conversion exceeds either an upper or lower threshold.
Additionally, a programmable interrupt persistence feature allows the user to determine how many consecutive exceeded thresholds are necessary to trigger an interrupt. Interrupt thresholds and persistence settings are configured independently for both ALS and proximity. This is accomplished with a proprietary current calibration technique that accounts for all variances in silicon, optics, package and most importantly IR LED output power.
This will eliminate or greatly reduce the need for factory calibration that is required for most discrete proximity sensor solutions. Each pulse has a 16? Interrupt — open drain. LED driver for proximity emitter — up to mA, open drain. All voltages are referenced to GND.
I2C serial clock input terminal — clock signal for I2C serial data. Power Supply voltage. Absolute Maximum Ratings over operating free-air temperature range unless otherwise noted? Parameter Power Supply voltage Digital voltage range Digital output current Storage temperature range?
Symbol VDD Min Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. Note: 1. All voltages are with respect to GND. The nominal and maximum values are shown under Proximity Characteristics. Optical measurements are made using small-angle incident radiation from light-emitting diode optical sources.
Visible nm LEDs and infrared nm LEDs are used for final product testing for compatibility with high-volume production. I2C Bus Timing Diagram 6 1. Normalized IDD vs. VDD 1. Normalized ALS Response vs. After a power-on-reset, the device is in the sleep mode. As soon as the PON bit is set, the device will move to the start state. If these states are enabled, the device will execute each function.
If the PON bit is set to a 0, the state machine will continue until all conversions are completed and then go into a low power sleep mode. This can lead to significant error when the infrared content of the ambient light is high such as with incandescent lighting due to the difference between the silicon detector response and the brightness perceived by the human eye. One of the photodiodes, referred to as the Ch0 channel, is sensitive to both visible and infrared light while the second photodiode is sensitive primarily to infrared light.
Two integrating ADCs convert the photodiode currents to digital outputs. The ADC digital outputs from the two channels are used in a formula to obtain a value that approximates the human eye response in units of Lux.
The transfers are double-buffered to ensure that invalid data is not read during the transfer. After the transfer, the device automatically moves to the next state in accordance with the configured state machine.
NOTE: In this document, the nomenclature uses the bit field name in italics followed by the register number and bit number to allow the user to easily identify the register and bit that controls the function. For example, the power on PON is in register 0, bit 0. This is represented as PON r0:b0. Note: 2.
Multiply by 87 the shift by 5 bits. Gain and Integration Time to Lux without IR With the programming versatility of the integration time and gain, it can be difficult to understand when to use the different modes. Figure 8 shows a log-log plot of the Lux vs. The intercept with a count of 1 shows the resolution of each setting.
The Lux values in the table increase as the SF increases spectral attenuation increases. The Lux values in the table decrease as the IR Factor decreases. There are many factors that will impact the decision on which value to use for integration time and gain. With this value, the resolution will be 1. If higher resolution is needed, a longer integration time may be needed. In this case, the integration time should be programmed in multiples of The light level is the next determining factor for configuring device settings.
Under bright conditions, the count will be fairly high. As a general rule, it is recommended to have a Ch0 channel count of at least 10 to accurately apply the Lux equation. The digital accumulation is limited to 16 bits, which occurs at an integration time of ms.
This is the maximum recommended programmed integration time before increasing the gain. This feature eliminates the need to use a current limiting resistor to control LED current. The LED drive current can be configured for The number of LED pulses can be programmed to a value of 1 to pulses as needed.
Increasing the number of LED pulses at a given current will increase the sensor sensitivity. Sensitivity grows by the square root of the number of pulses. Each pulse has a 16 mS period. The module package design has been optimized for minimum package foot print and short distance proximity of mm typical.
The spacing between the glass surface and package top surface is critical to controlling the crosstalk. If the package to top surface spacing gap, window thickness and transmittance are met, there should be no need to add additional components such as a barrier between the LED and photodiode.
The device has a package Z height of 1. By integrating the micro-optics in the package, the IR energy emitted can be reduced thus conserving the precious battery life in the application. The system designer has the ability to optimize their designs for slim form factor Z height as well as improve the proximity sensing, save battery power and disable the touch screen in a cellular phone.
Windows Thickness, t Figure PS Output vs. Figure 11b. This feature allows the user to specify a number of conversion cycles for which an event exceeding the ALS interrupt threshold must persist APERS or the proximity interrupt threshold must persist PPERS before actually generating an interrupt. Refer to the register descriptions for details on the length of the persistence.
The device starts in the sleep mode. The PON bit is written to enable the device. If the PEN bit is set, the state machine will step through the proximity states of proximity accumulate and then proximity ADC conversion. As soon as the conversion is complete, the state machine will move to the following state. If the WEN bit is set, the state machine will then cycle through the wait state. When the wait counter terminates, the state machine will step to the ALS state.
In this case, a minimum of 1 integration time step should be programmed. The ALS state machine will continue until it reaches the terminal count at which point the data will be latched in the ALS register and the interrupt set, if enabled.
Wiring the APDS 9930 Ambient Light Sense / APDS 9960 RGB Gesture Sensor With Microcontroller
【Avago Technologies】 フォトセンサ (APDS-9900)