Zakładka z wyszukiwarką danych komponentów |
|
ISL29030AIROZ-EVALZ Arkusz danych(PDF) 9 Page - Intersil Corporation |
|
ISL29030AIROZ-EVALZ Arkusz danych(HTML) 9 Page - Intersil Corporation |
9 / 16 page ISL29030A 9 FN7722.1 March 31, 2011 Principles of Operation I2C Interface The ISL29030A I2C interface slave address is internally hardwired as 0b1000100. Figure 2 shows a sample one-byte read. 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 transaction begins with the master asserting a start condition (SDA falling while SCL remains high). The first transmitted byte is initiated by the master and includes seven address bits and a R/W bit. The slave is responsible for pulling SDA low during the ACK bit after every transmitted byte. Each I2C transaction ends with the master asserting a stop condition (SDA rising while SCL remains high). For more information about the I2C standard, please consult the Philips™ I2C specification documents. Photodiodes and ADCs The ISL29030A contains two photodiode arrays that convert photons (light) into current. The ALS photodiodes are constructed to mimic the human eye wavelength response curve to visible light (see Figure 7). The ALS photodiode current output is digitized by a 12-bit ADC in 100ms. These 12 bits can be accessed by reading from I2C registers 0x9 and 0xA when the ADC conversion is completed. The ALS converter is a charge-balancing, integrating, 12-bit ADC. Charge-balancing is best for converting small current signals in the presence of periodic AC noise. Integrating over 100ms highly rejects both 50Hz and 60Hz light flicker by picking the lowest-integer number of cycles for both 50Hz/60Hz frequencies. The proximity sensor is an 8-bit ADC that operates in a similar fashion. When proximity sensing is enabled, the IRDR pin drives a user-supplied infrared LED, the emitted IR reflects off an object (i.e., a human head) back into the ISL29030A, and a sensor converts the reflected IR wave to a current signal in 0.54ms. The ADC subtracts the IR reading before and after the LED is driven (to remove ambient IR such as sunlight) and converts this value to a digital count stored in Register 0x8. The ISL29030A is designed to run two conversions concurrently: a proximity conversion, and an ALS (or IR) conversion. Please note that because of the conversion times, the user must let the ADCs perform one full conversion first before reading from I2C Registers PROX_DATA (wait 0.54ms) or ALSIR_DT1/2 (wait 100ms). The timing between ALS and Prox conversions is arbitrary, as shown in Figure 3. The ALS runs continuously, with new data available every 100ms. The proximity sensor runs continuously, with a time between conversions decided by PROX_SLP (Register 1 Bits [6:4]). Ambient Light and IR Sensing The ISL29030A is set for ambient light sensing when Register bit ALSIR_MODE = 0 and ALR_EN = 1. The light-wavelength response of the ALS appears as shown in Figure 6. ALS measuring mode (as opposed to IR measuring mode) is set by default. When the part is programmed for infrared (IR) sensing (ALSIR_MODE = 1; ALS_EN = 1), infrared light is converted into a current and is digitized by the same ALS ADC. The result of an IR conversion is strongly related to the amount of IR energy incident on the sensor, but it is unitless and is referred to in digital counts. Proximity Sensing When proximity sensing is enabled (PROX_EN = 1), the external IR LED is driven through the IRDR pin for 0.1ms by the built-in IR LED driver. The amplitude of the IR LED current depends on Register 1 bit 3: PROX_DR. If this bit is low, the load sees a fixed ALS ACTIVE 100ms 100ms 100ms PROX SENSOR ACTIVE IRDR (CURRENT DRIVER) ALS CONVERSION TIME = 100ms (FIXED) 0.54ms FOR PROX CONVERSION SERIES OF CURRENT PULSES TOTALING 0.1ms SLEEP TIME (PROX_SLP) 100ms 100ms SEVERAL µs BETWEEN CONVERSIONS TIME TIME TIME FIGURE 3. TIMING DIAGRAM FOR PROX/ALS EVENTS - NOT TO SCALE |
Podobny numer części - ISL29030AIROZ-EVALZ |
|
Podobny opis - ISL29030AIROZ-EVALZ |
|
|
Link URL |
Polityka prywatności |
ALLDATASHEET.PL |
Czy Alldatasheet okazała się pomocna? [ DONATE ] |
O Alldatasheet | Reklama | Kontakt | Polityka prywatności | Linki | Lista producentów 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 |