Electronic Components Datasheet Search |
|
ISL29033 Datasheet(PDF) 6 Page - Intersil Corporation |
|
ISL29033 Datasheet(HTML) 6 Page - Intersil Corporation |
6 / 15 page ISL29033 6 FN7656.5 September 28, 2016 Submit Document Feedback Principles of Operation Photodiodes and ADC The ISL29033 contains two photodiode arrays that convert light into current. The spectral response for ambient light sensing and infrared (IR) sensing is shown in Figure 8 on page 12. After light is converted to current during the light signal process, the current output is converted to digital by a built-in 16-bit Analog-to-Digital Converter (ADC). An I2C command reads the ambient light or IR intensity in counts. The converter is a charge-balancing integrating type 16-bit ADC. The chosen method for conversion is best for converting small current signals in the presence of an AC periodic noise. A 100ms integration time, for instance, highly rejects a 50Hz and 60Hz power line noise simultaneously. See “Integration and Conversion Time” on page 9. The built-in ADC offers user flexibility in integration time or conversion time. There are two timing modes: Internal timing mode and external timing mode. In internal timing mode, integration time is determined by an internal oscillator (fOSC) and the n-bit (n = 4, 8, 12, 16) counter inside the ADC. In external timing mode, integration time is determined by the time between two consecutive I2C External Timing Mode commands. A good balance of integration time and resolution (depending on application) is required for optimal results. The ADC has an I2C programmable range select to dynamically accommodate various lighting conditions. For very dim conditions, the ADC can be configured at its lowest range (Range 1) in the ambient light sensing. Low-Power Operation The ISL29033 initial operation is at the power-down mode after a supply voltage is provided. The data registers contain the default value of 0. When the ISL29033 receives an I2C command to do a one-time measurement from an I2C master, it starts an ADC conversion with light sensing. It goes to power-down mode automatically after one conversion is finished and keeps the conversion data available for the master to fetch anytime afterwards. The ISL29033 continuously does the ADC conversion with light sensing if it receives an I2C command of continuous measurement. It continuously updates the data registers with the latest conversion data. The ISL29033 goes to power-down mode after it receives the I2C command of power-down. Ambient Light There are two operational modes in ISL29033: programmable continuous ALS sensing and programmable continuous IR sensing. These two modes can be programmed in series to fulfill the application needs. The detailed program configuration is shown in the Figure 1 on page 1. When the part is programmed for ambient light sensing, the ambient light with wavelength within the “Ambient Light Sensing” spectral response curve in Figure 8 is converted into current. With ADC, the current is converted to an unsigned n-bit (up to 16 bits) digital output. When the part is programmed for infrared (IR) sensing, the IR light with wavelength within the “IR Sensing” spectral response curve in Figure 8 is converted into current. With ADC, the current is converted to an unsigned n-bit (up to 16 bits) digital output. Interrupt Function The active low-interrupt pin is an open-drain pull-down configuration. The interrupt pin serves as an alarm or monitoring function to determine whether the ambient light level exceeds the upper threshold or goes below the lower threshold. Note that the function of ADC conversion continues without stopping after interrupt is asserted. If the user needs to read the ADC count that triggers the interrupt, reading should be done before the data registers are refreshed by subsequent conversions. The user can also configure the persistency of the interrupt pin. This reduces the possibility of false triggers, such as noise or sudden spikes in ambient light conditions. An unexpected camera flash, for example, can be ignored by setting the persistency to eight integration cycles. ALS Ranges Considerations When measuring ALS counts higher than 30000 counts on Range 1 of the 16-bit ADC, switch to Range 2 (change [1 to 0] bits of Register 1 from 00 to 01) and remeasure the ALS counts and other data to change to Range 3 and Range 4. This recommendation pertains only to applications in which light incident on the sensor is IR-heavy and is distorted by tinted glass that increases the ratio of infrared to visible light. VDD Power-Up and Power Supply Considerations Upon power-up, ensure a VDD slew rate of 0.5V/ms or greater. After power-up, or if the power supply temporarily deviates from specification (2.25V to 3.63V), the following step is recommended: write 0x00 to register 0x00. Wait a few seconds and then rewrite all registers to the desired values. A hardware reset method can be used, if preferred, instead of writing to the test registers. For this method, set VDD =0V for 1 second or more, power back up at the required slew rate and write the registers to the desired values. Power-Down To put the ISL29033 into a power-down state, the user can set [7 to 5] bits to 0 in Register 0. Or more simply, set all of Register 0 to 0x00. I2C Interface There are eight 8-bit registers available inside the ISL29033. The two command registers define the operation of the device. The command registers do not change until the registers are overwritten. The two 8-bit data read-only registers are for the ADC output. The data registers contain the ADC's latest digital output, or the number of clock cycles in the previous integration period (Figure 2 on page 7). The ISL29033 I2C interface slave address is internally hard-wired as 1000100. When 1000100x, with x as R or W, is sent after the start condition, the device compares the first seven bits of this byte to its address and matches. Figure 3 on page 7 shows a sample one- byte read and Figure 4 on page 8 shows a sample one-byte write. The I2C bus master always drives the SCL (clock) line, while either the master or the slave can drive the SDA (data) line. Every I2C |
Similar Part No. - ISL29033 |
|
Similar Description - ISL29033 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |