ADUX1020BCPZRL7

Photometric Sensor for Gesture and Proximity ADUX1020 Data Sheet FEATURES GENERAL DESCRIPTION Multifunction photometric sensor and signal conditioning Fully integrated AFE, ADC, LED driver, and timing core Usable for multiple optical measurement applications, including gesture control and proximity sensing Enables an ambient light rejection capability using both optical and analog filtering On-chip programmable flexible current sink for external LED High sensitivity and signal-to-noise ratio (SNR) High resolution position measurement Gesture recognition with 0.5 cm to 15 cm range Proximity sensing to 20 cm 400 kHz I2C interface Gesture/proximity works under infrared (IR) transparent glass or other materials Simple integration with optics; no need for precise alignment and no lens is required Low power operation 1.8 V analog/digital core 8-lead, 2 mm × 3 mm, 0.65 mm height LFCSP The ADUX1020 is a highly efficient photometric sensor with an integrated 14-bit analog-to-digital converter (ADC) and a 20-bit burst accumulator that works in concert with a flexible light emitting diode (LED) driver. It is designed to modulate a LED and measure the corresponding optical return signal. The digital engine includes circuitry and control for data aggregation and proximity detection. The data output and device configuration use a 1.8 V I2C interface. The control circuitry includes flexible LED pulse width and period generation combined with synchronous detection. This circuitry is complemented by a low noise, low power, and wide dynamic range configurable analog front end (AFE), clock generation, LED driver, and digital logic for position and smart sample mode (event driven x, y coordinates, relative z data). This complete AFE features ambient light rejection, avoiding corruption due to external interference. APPLICATIONS One inexpensive standard surface mount, broad angle or narrow angle IR LED (depending upon application) is required. This LED mounts externally to the ADUX1020. Gesture for user interface (UI) control in portable devices Industrial/automation monitoring Presence detection Angle sensing Packaged in a small, clear mold, 2 mm × 3 mm, 8-lead LFCSP, the ADUX1020 is specified over an operating temperature range of −40°C to +85°C. FUNCTIONAL BLOCK DIAGRAM ADUX1020 AFE: SIGNAL CONDITIONING SDA SCL POSITION SENSOR ADC GESTURE ENGINE DIGITAL INTERFACE CONTROL LOGIC INT VREF LED DRIVER 11429-001 LEDX Figure 1. Rev. A Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 ©2016 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com ADUX1020 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Sample/Gesture Mode ............................................................... 10 Applications ....................................................................................... 1 Use of Multiple Modes ............................................................... 10 General Description ......................................................................... 1 Adjustable Sampling Frequency ............................................... 11 Functional Block Diagram .............................................................. 1 Normal Mode Operation and Data Flow ................................ 11 Revision History ............................................................................... 2 AFE Operation............................................................................ 12 Specifications..................................................................................... 3 I2C Serial Interface ..................................................................... 13 Temperature and Power Specifications ..................................... 3 Typical Connection Diagram ................................................... 14 Performance Specifications ......................................................... 4 LED Driver Pin and LED Supply Voltage ............................... 14 Analog Specifications ................................................................... 5 LED Driver Operation ............................................................... 14 Digital Specifications ................................................................... 6 Determining the Average Current ........................................... 15 Timing Specifications .................................................................. 6 LED Inductance Considerations .............................................. 15 Absolute Maximum Ratings ............................................................ 7 Recommended Start-Up Sequence .......................................... 15 Thermal Resistance ...................................................................... 7 Clocks and Timing Calibration ................................................ 15 ESD Caution .................................................................................. 7 Reading Data ............................................................................... 16 Pin Configuration and Function Descriptions ............................. 8 Calculating Current Consumption .......................................... 17 Typical Performance Characteristics ............................................. 9 Recommended Soldering Profile ................................................. 19 Theory of Operation ...................................................................... 10 Complete Register Listing ............................................................. 20 Idle Mode ..................................................................................... 10 Outline Dimensions ....................................................................... 31 Standby Mode ............................................................................. 10 Ordering Guide .......................................................................... 31 Proximity Mode .......................................................................... 10 REVISION HISTORY 6/2016—Revision A: Initial Version Rev. A | Page 2 of 31 Data Sheet ADUX1020 SPECIFICATIONS TEMPERATURE AND POWER SPECIFICATIONS Table 1. Operating Conditions Parameter TEMPERATURE RANGE Operating Range Storage Range POWER SUPPLY VOLTAGES Input Supply Voltage Supply Voltage for the LEDs Symbol Test Conditions/Comments Min Typ −40 −65 VDD VLED 1.7 1.8 3.3 VLED depend on the LED selected Max Unit +85 +150 °C °C 1.9 V V VDD = 1.8 V, ambient temperature, unless otherwise noted. Table 2. Current Consumption Parameter TOTAL POWER CONSUMPTION VDD STANDBY MODE CURRENT SUPPLY CURRENT 1.8 V VDD Peak 1.8 V VDD Average Example VDD Average Average VLED Example VLED Average 1 Pulse (Proximity) 8 Pulses (Sample/Gesture) Symbol Test Conditions/Comments See the Calculating Current Consumption section Min IVDD_STANDBY IVDD_PEAK IVDD_AVG ILED_AVG Typ Max 3.5 Continuous maximum rate AFE operation See the Calculating Current Consumption section LED_OFFSET = 25 µs, LED_PERIOD = 19 µs, LED_PULSES = 8, LED peak current = 250 mA 1 Hz data rate; proximity mode 50 Hz data rate; proximity mode 820 Hz data rate; sample/gesture mode See the Calculating Current Consumption section Peak LED current = 250 mA, LED_PULSE width = 3 µs 1 Hz data rate 50 Hz data rate 820 Hz data rate 50 Hz data rate 820 Hz data rate Rev. A | Page 3 of 31 3.6 V may damage the device. In addition, a negative spike ≤ −0.3 V may also damage the device. Rev. A | Page 15 of 31 ADUX1020 Data Sheet Use the following steps to calibrate the 32 kHz clock by referencing the timer of the controlling microprocessor. Do not set the I2C output rate to a speed that overloads the I2C FIFO. If the microprocessor is fully available for handling clock calibration operation at this time, and its I2C speed is set to 400 kHz, the I2C throughput will be more than 2 kHz. 1. 2. 3. 4. 5. 6. 7. Set the projected output rate to 820 Hz by writing 0x1C to Register 0x44. Set up and run the device in sample mode by writing 0x8 to Register 0x45, Bits[3:0]. Flush the I2C FIFO by writing Register 0x49, Bit 15. Poll data from I2C FIFO for 0.5 sec by repeatedly reading Register 0x60. Count the number of sample sets for 1 sec. Calculate the actual output rate equal to the sample set count divided by 0.5. Adjust the 32 kHz oscillator trim value by writing to Register 0x18, Bits[3:0] with the appropriate value. Repeat Step 1 through Step 5 until the actual measured output data rate is as close to 820 Hz as possible. If the output data rate is below 820 Hz, increment the trim value, and if it is above 820 Hz, decrement the trim value. Calibrating the 32 MHz Clock written to the FIFO. Data packets are written to the FIFO at the output data rate. Output Data Rate = fSAMPLE/N where: fSAMPLE is the sampling frequency. N is the averaging factor for sample/gesture mode or proximity mode. A data packet for the FIFO consists of a complete sample for either proximity mode or sample/gesture mode. In proximity mode, the device can store either only intensity i data as 2 bytes or x, y, and i data as 6 bytes. In sample/gesture mode, the device always sends 4 bytes to the FIFO. To ensure that data packets are intact, new data is written only to the FIFO if there is sufficient space for a complete packet. Any new data that arrives when there is not enough space is lost. The FIFO continues to store data when sufficient space exists. Always read FIFO data in complete packets to ensure that data packets remain intact. The number of bytes currently stored in the FIFO is available in Register 0x49, Bits[14:8]. A dedicated FIFO interrupt is also available and automatically generates when a specified amount of data is written to the FIFO. The 32 MHz oscillator on the ADUX1020 may also have up to 30% variation in frequency due to the variation of on-chip RC components. Use the following steps to calibrate the 32 MHz clock by comparing it with the 32 kHz clock. To read data from the FIFO using an interrupt-based method, use the following procedure: 1. 2. 2. 3. 4. 5. 6. 7. Enable the 32 kHz oscillator by writing Register 0x18, Bit 7. Enable the 32 MHz oscillator by writing Register 0x32, Bit 3 and Bit 11. Enable clock calibration by writing Register 0x30, Bit 5. Read the calibration result from Register 0x0A, Bits[11:0]. Compare the calibration result. The calibration is complete when the result read is as close as possible to the optimal value of 2000. If it is not, increment the trim value if the result is below 2000, or decrement if it is above 2000. Write the new trim value and then write 1 to Register 0x30, Bit 5. Note that typically two trim values produce calibration results that straddle the optimal result. Choose the closest. Write the new trim value in Register 0x1A, Bits[7:0]. Disable calibration by writing 0 to Register 0x30, Bit 5. 1. 3. 4. 5. 6. READING DATA The ADUX1020 provides multiple methods for accessing the sample data. Interrupt signaling is available to simplify timely data access. The FIFO is available to loosen the system timing requirements for data accesses. Reading Data Using the FIFO The ADUX1020 includes a 64-byte FIFO memory buffer that can store data from either sample/gesture mode or proximity mode. Register 0x45, Bits[7:4] select the kind of data to be Rev. A | Page 16 of 31 In standby mode, set the configuration of sample/gesture or proximity mode as desired for operation. Write to Register 0x45, Bits[7:4] with the desired data format for each mode. Set FIFO_TH in Register 0x1F, Bits[11:8] to the interrupt threshold. A good value for this is the number of 16-bit words in a data packet minus 1, which causes an interrupt to generate when at least one complete packet is in the FIFO. Enable the FIFO interrupt by writing INT_MASK, Register 0x48, Bits[7:0]. Also, configure the interrupt pin (INT) by writing the appropriate value to Register 0x1C, Bit 2. Enter sample/gesture or proximity mode by setting Register 0x45, Bits[3:0] to the desired value. When an interrupt occurs, the following results: a. Note that there is no requirement to read the FIFO_ STATUS register because the interrupt is generated only if there is one or more full packets. Optionally, the interrupt routine can check for the presence of more than one available packet by reading this register. b. Force the 32 MHz clock on by writing 0x0F4F to Register 0x32. c. Read a complete packet using one or more multiword accesses using Register 0x60. Reading the FIFO automatically frees the space for new samples. d. Set the 32 MHz clock to be controlled by the internal state machine by writing 0x40 to Register 0x32. Data Sheet ADUX1020 4. The interrupt automatically clears when enough data is read from the FIFO to bring the data level below the threshold. To read data from the FIFO in a polling method, use the following procedure: 1. 2. 3. In standby mode, set the configuration of gesture/sample mode or proximity mode as desired for operation. Write Register 0x45, Bits[7:4] with the desired data format. Enter proximity or sample/gesture mode by setting Register 0x45, Bits[3:0] to the desired setting. Next, begin the polling operations, by taking the following steps: 1. 2. 3. 4. Wait for the polling interval to expire. Read the FIFO_STATUS bits (Register 0x49, Bits[15:8]). If FIFO_STATUS is greater than or equal to the packet size, read a packet using the following steps: a. Force the 32 MHz clock on by writing 0x0F4F to Register 0x32. b. Read a complete packet using one or more multiword accesses using Register 0x60. Reading the FIFO automatically frees the space for new samples. c. Set the 32 MHz clock to be controlled by the internal state machine by writing 0x0040 to Register 0x32. When a mode change is required, or any other disruption to normal sampling is necessary, clear the FIFO. Use the following procedure to clear the state and empty the FIFO: a. Enter idle mode by setting Register 0x45, Bits[3:0] to 0xF. b. Force the 32 MHz clock on by writing 0x0F4F to Register 0x32. c. Write 1 to Register 0x49, Bit 15. d. Write 0x40 to Register 0x32 to set the 32 MHz clock to be controlled by the internal state machine. Reading Data from Registers Using Interrupts The latest sample data is always available in the data registers and is updated simultaneously at the end of each time slot. The data value for each photodiode channel is available as a 16-bit value in Register 0x00 through Register 0x03 (READX1, READX2, READY1, and READY2) for sample/gesture mode, and Register 0x04 through Register 0x06 (SAMPLEI, SAMPLEX, and SAMPLEY) for proximity mode. If allowed to reach their maximum value, Register 0x00 through Register 0x06 clip. Sample interrupts are available to indicate when the registers are updated and can be read. To use the interrupt for a given time slot, use the following procedure: 1. 2. 3. The interrupt handler must perform the following: a. Read Register 0x49 and observe Bits[7:0] to confirm which interrupt has occurred. This step is not required if only one interrupt is in use. b. Read the data registers before the next sample can be written. The system must have interrupt latency and service time short enough to respond before the next data update based on the output data rate. c. Write 0x0 to Bits[7:0] in Register 0x49 to clear the interrupt. CALCULATING CURRENT CONSUMPTION The current consumption of the ADUX1020 depends on the user selected operating configuration, as described in the Equation 7, Equation 8, and Equation 9. Total Power Consumption To calculate the total power consumption, use Equation 7. Total Power = IVDD_AVG × VDD + ILED_AVG × VLED (7) where: IVDD_AVG is the VDD average. VDD is the ADUX1020 supply voltage. ILED_AVG is the average LED current. VLED is the LED supply voltage. Average VDD Supply Current To calculate the average VDD supply current, use Equation 8. IVDD_AVG = DR × (IAFE × tMODE + IPROC) + IVDD_STANDBY (8) where: DR is the data rate in Hz. IAFE = 8.9 + (LEDPEAK − 25)/225, where LEDPEAK is the peak LED current expressed in mA. tMODE = LED_OFFSET_x + LED_PERIOD_x × PULSE_COUNT_x. Note that LED_OFFSET_x is the pulse start time offset expressed, LED_PERIOD_x is the pulse period expressed in seconds, PULSE_COUNT_x is the number of pulses, and x is either PROX or GEST depending on the mode of operation. IPROC is an average current associated with the processing time. For sample/gesture mode, IPROC = 0.64 × 10−3, and for proximity mode, IPROC = 0.51 × 10−3. IVDD_STANDBY = 3.5 × 10−3 mA. Enable the sample interrupt by writing a 0 to the appropriate bit in Register 0x48. Configure the interrupt pin by writing the appropriate value to the bits in Register 0x1C. An interrupt generates when the data registers are updated. Rev. A | Page 17 of 31 ADUX1020 Data Sheet Average VLEDA Supply Current To calculate the average VLED supply current, use Equation 9. ILED_AVG = (LED_WIDTH/1 × 106) × LEDPEAK × DR × PULSE_COUNT (9) where: LED_WIDTH is the on time for the LED pulse, in µs. PULSE_COUNT is the number of LED pulses per sample. Tuning the Pulse Count After the LED peak current and TIA gain are optimized, increasing the number of pulses per sample increases the SNR by the square root of the number of pulses. There are two ways to increase the pulse count. The pulse count registers (Register 0x21, Bits[13:8] for sample/gesture mode, and Register 0x23, Bits[13:8] for proximity mode) change the number of pulses per internal sample. Register 0x46, Bits[6:4] for sample/gesture mode and Bits[2:0] for proximity mode controls the number of internal samples that are averaged together before the data is sent to the output. Therefore, the number of pulses per sample is the pulse count register multiplied by the number of subsequent samples being averaged. In general, the internal sampling rate increases as the number of internal sample averages increase to maintain the desired output data rate. The SNR/Watt is most optimal with pulse count values of 16 or less. Above pulse count values of 16, the square root relationship does not hold in the pulse count register. However, this relationship continues to hold when averaged between samples using Register 0x46. Note that increasing LED peak current increases SNR almost directly proportional to LED power, whereas increasing the number of pulses by a factor of n results in only a nominal√(n) increase in SNR. When using the sample sum/average function (Register 0x46), the output data rate decreases by the number of summed samples. To maintain a static output data rate, increase the sample frequency (Register 0x40, Bits[3:0] for sample/gesture mode, Bits[7:4] for proximity mode) by the same factor as that selected in Register 0x46. For example, for a 100 Hz output data rate and a sample sum/average of four samples, set the sample frequency to 400 Hz. Rev. A | Page 18 of 31 Data Sheet ADUX1020 RECOMMENDED SOLDERING PROFILE Figure 12 and Table 12 provide details about the recommended soldering profile. CRITICAL ZONE TL TO TP P P L TSMAX L SMIN 11429-012 S Figure 12. Recommended Soldering Profile Table 12. Recommended Soldering Profile Profile Feature Average Ramp Rate (TL to TP) Preheat Minimum Temperature (TSMIN) Maximum Temperature (TSMAX) Time (TSMIN to TSMAX) (tS) TSMAX to TL Ramp-Up Rate Time Maintained Above Liquidous Temperature Liquidous Temperature (TL) Time (tL) Peak Temperature (TP) Time Within 5°C of Actual Peak Temperature (tP) Ramp-Down Rate Time from 25°C to Peak Temperature (t25°C TO PEAK) Condition (Pb-Free) 3°C/sec maximum 150°C 200°C 60 sec to 180 sec 3°C/sec maximum 217°C 60 sec to 150 sec +260 (+0/−5)°C