VCNL4100 Datasheet, PDF (12/17 Pages) Vishay Siliconix – High Sensitivity Long Distance Proximity and Ambient Light Sensor with I2C Interface

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VCNL4100
Vishay Semiconductors
Threshold Window Setting
• ALS Threshold Window Setting (Applying ALS INT)
Register: ALS_THDH_L and ALS_THDH_M define 16-bit ALS high threshold data for LSB byte and MSB byte. Register:
ALS_THDL_L and ALS_THDL_M define 16-bit ALS low threshold data for LSB byte and MSB byte. As long as ALS INT
function is enabled, INT will be asserted once the ALS data exceeds ALS_THDH or goes below ALS_THDL. To easily define
the threshold range, multiply the value of the resolution (lx/step) by the threshold level (refer table 17).
TABLE 17 - ALS RESOLUTION AND MAXIMUM DETECTION RANGE
ALS_IT
(7 : 6)
ALS_IT
INTEGRATION TIME
SENSITIVITY
(lx/step)
MAXIMUM DETECTION
RANGE
(lx)
(0, 0)
80 ms
0.08
5243
(0, 1)
160 ms
0.04
2621
(1, 0)
320 ms
0.02
1311
(1, 1)
640 ms
0.01
655

The following is an example of the application for ALS_IT = 160 ms. If ALS_THDH = 07D0(HEX) and ALS_THDL = 03E8(HEX),
then the ALS INT will not asserted if the ALS value does not exceed 80 lx [07D0(HEX) = 2000 steps x 0.04 lx/step = 80 lx] or
lower than 40 lx [03E8(HEX) = 1000 steps x 0.04 lx/step = 40 lx.
• ALS Persistence
The ALS INT is asserted as long as the ALS value is higher or lower than the threshold window when ALS_PERS
(1 / 2 / 4 / 8 times) is set to one time. If ALS_PERS is set to four times, then the ALS INT will not be asserted if the
ALS value is not over (or lower) than the threshold window for four continued refresh times (integration time).
• Programmable PS Threshold
VCNL4100 provides both high and low thresholds 8-bit data setting for proximity sensor. (register: PS_THDL, PS_THDH) that
fulfills different mechanical designs with the best proximity detection capability for any kind of objects.
• PS Persistence
The PS persistence function (PS_PERS 1 / 2 / 3 / 4) helps to avoid false trigger of the PS INT. For example, if
PS_PERS = 3 times, the PS INT will not be asserted unless the PS value is greater than the PS threshold (PS1_THDH)
value for three periods of time continuously.
Data Access
All VCNL4100 command registers are readable. To access 16-bit high resolution ALS output data, it is suitable to use read word
protocol to read out data by just one command at register: ALS_Data_L and ALS_Data_M. To represent the 16-bit data of ALS,
it has to apply two bytes. One byte is for LSB, and the other byte is for MSB as shown in table 18. In terms of reading out 8-bit
PS data, host just need to access register: PS_Data.
TABLE 18 - 16-BIT ALS DATA FORMAT
VCNL4100
Bit
15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Register
ALS_Data_M
ALS_Data_L
Interrupt (INT)
VCNL4100 has ALS and PS interrupt feature operated by a single pin “INT”. The purpose of the interrupt feature is to actively
inform the host once INT has been asserted. With the interrupt function applied, the host does not need to constantly pull data
from the sensor, but to only read data from the sensor when receiving interrupt request from the sensor. As long as the host
enables ALS interrupt (register: ALS_INT_EN) or PS interrupt (register: PS_INT) function, the level of INT pin (pin 8) is able to be
pulled low once INT asserted. All of registers are accessible even INT is asserted.
ALS INT asserted when ALS value crosses over the value set by register: ALS_THDH or is lower than the value set by
register: ALS_THDL.
PS INT asserted when PS value crosses over the value set by register: PS_THDH or is lower than the value set by
register: PS_THDL.
Rev. 1.2, 30-Aug-16
12
Document Number: 84319
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