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ISL29038IROZ-T7 参数 Datasheet PDF下载

ISL29038IROZ-T7图片预览
型号: ISL29038IROZ-T7
PDF下载: 下载PDF文件 查看货源
内容描述: [Low Power Ambient Light and Proximity Sensor with Enhanced Infrared Rejection]
分类和应用: 光电二极管
文件页数/大小: 15 页 / 560 K
品牌: XICOR [ XICOR INC. ]
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ISL29038  
Registers 0x01, 0x02 are used to configure the primary proximity  
The ALS runs continuously with new data available every 90ms.  
The proximity sensor runs continuously with a time between  
conversions controlled by PROX_SLP (Reg 0x01[6:4]).  
and ALS parameters. Register 0x03 is used for optimizing IR  
compensation in ALS measurements. A procedure to optimize IR  
compensation is described in “ALS IR Compensation” on page 11.  
Ambient Light Sensing  
Register 0x04 is the Interrupt Configuration and Status Register,  
and is used primarily to indicate interrupt events from proximity  
and ALS measurements. A PWR_FAIL bit to indicate a  
‘Brown-Out’ event is available and is set in case of a power supply  
interruption. A ‘Brown-Out’ event does not generate a hardware  
interrupt. The host micro-controller must clear this bit by writing a  
‘0’ to Reg 0x04[4].  
The ISL29038 is set for ambient light sensing when Register bit  
ALS_EN = 1. Four measurement ranges from 125 Lux to 4000 Lux  
are available. The ALS measurement range is configured via Reg  
0x02[1:0].  
Proximity Sensing  
When proximity sensing is enabled (PROX_EN = 1), the external  
IR LED is driven for 100µs by the built-in IR LED driver through  
the IRDR pin.  
Register 0x04 is also used to configure ALS & Proximity interrupt  
persistency and the operation of the INT pin.  
Registers 0x05 and 0x06 are used to set the proximity ‘LOW’ and  
‘HIGH’ threshold for proximity interrupt event generation.  
ALS CONVERSION TIME =  
SEVERAL µs BETWEEN  
90ms (FIXED)  
CONVERSIONS  
Registers 0x07, 0x08 and 0x09 are used to set the ALS ‘LOW’  
and ‘HIGH’ threshold. Two 12-bit numbers span three address  
locations as shown in Table 1.  
ALS  
ACTIVE  
90ms  
90ms  
90ms  
90ms  
90ms  
TIME  
TIME  
Data registers 0x0A holds result of proximity conversion. The  
proximity result should be validated by ‘Washout’ bit in Reg  
0x0D[0]. Registers 0x0B and 0x0C hold result of an ALS  
measurement.  
0.50ms FOR PROX  
CONVERSION  
PROX  
SENSOR  
ACTIVE  
The ALS data is 12 bits wide. Least Significant Byte of the ALS  
data is available at address 0x0C and Most Significant Byte  
(MSB) of ALS data is available at address 0x0B. The MSB is right  
justified, i.e., the upper nibble is always zero and lower nibble  
contains four data bits.  
SERIES OF  
CURRENT PULSES  
TOTALING 0.09ms  
IRDR  
(CURRENT  
DRIVER)  
TIME  
Register 0x0D[7:1] contains ambient IR measurement in  
proximity measurement phase. This measurement is for  
detecting ambient Washout condition, which is indicated by Reg  
0x0D[0] being ‘HIGH’. Proximity ‘Washout’ is described in  
“Proximity Ambient Washout Detection” on page 11.  
SLEEP TIME  
(PROX_SLP)  
FIGURE 10. TIMING DIAGRAM FOR PROX/ALS EVENTS - NOT TO SCALE  
The IR LED current depends on PROX_DRV (Reg 0x01[1:0]). Drive  
current settings are as shown in Table 1. IR LED drive is in high  
impedance state when not active.  
A software reset can be initiated by writing 0x38 to Reg 0x0E.  
ISL29038 Operation  
Photodiodes and ADCs  
The ISL29038 contains two photodiode arrays, which convert  
photons (light) into current. The ALS photodiodes are designed to  
mimic the human eye’s wavelength response curve to visible light.  
The ALS photodiodes’ current output is digitized by a 12-bit ADC.  
When the IR from the LED reaches an object and gets reflected  
back to the ISL29038, the reflected IR light is converted into a  
current. This current is converted to digital data using an 8-bit  
ADC. The proximity measurement takes 0.5ms for one  
conversion including the 90μs LED drive time. The period  
between proximity measurements is determined by PROX_SLP  
(sleep time) in Reg 0x01[4:2].  
The ALS ADC output is accessed by reading from Reg 0x0B and  
0x0C when the ADC conversion is completed.  
Average LED driving current consumption is given by Equation 1.  
I
× 90μs  
lRDR;PEAK  
(EQ. 1)  
The ALS ADC converter uses a charge-balancing architecture.  
Charge-balancing is best suited for converting small current signals  
in the presence of periodic AC noise. ISL29038 targets an  
integration time of 90ms, which can vary ±15% from nominal. The  
ALS integration time is intended to minimize 60Hz flicker.  
I
= ----------------------------------------------------  
lRDR;AVE  
T
SLEEP  
A typical IRDR scheme is 250mA pulses every 400ms, averaging  
about 56μA DC.  
Total Current Consumption  
Total current consumption is the sum of I and I . The IRDR  
pin sinks current and the average IRDR current is calculated using  
The proximity sensor uses an 8-bit ADC, which operates in a  
similar fashion. The IRDR pin drives (pulses) an infrared LED, the  
emitted IR reflects off an object back into the ISL29038, and the  
photo diodes convert the reflected IR to a current signal in  
0.5ms. The ADC subtracts the IR reading before and after the  
LED is driven to remove ambient IR contribution.  
DD IRDR  
Equation 1. I depends on voltage and the mode-of-operation.  
DD  
For simplicity, Equation 1 ignores proximity ADC conversion time  
since it is much smaller than the sleep time.  
FN7851.0  
October 12, 2012  
10