Data Sheet

VCNL4040
www.vishay.com
Vishay Semiconductors
Rev. 1.4, 02-Mar-15
12
Document Number: 84274
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Adjustable Sampling Time
VCNL4040’s LED driver drives the internal IRED with the “LED CATHODE” pin by a pulsed duty cycle. The IRED on / off duty
ratio can be set in register: PS_Duty which is related to the current consumption and PS response time. The higher the duty
ratio, the faster the response time achieved with higher power consumption. For example, PS_Duty = 1/320, peak IRED current
= 100 mA, averaged current consumption is 100 mA/320 = 0.3125 mA.
Initialization
VCNL4040 includes default values for each register. As long as power is on, it is ready to be controlled by host via I
2
C bus.
Threshold Window Setting
• ALS Threshold Window Setting (Applying ALS INT)
Register: ALS_THDH_L and ALS_THDH_M defines 16-bit ALS high threshold data for LSB byte and MSB byte. Register:
ALS_THDL_L and ALS_THDL_M defines 16-bit ALS low threshold data for LSB byte and MSB byte. As long as ALS INT
function is enabled, INT will be triggered once the ALS data exceeds ALS_THDH or goes below ALS_THDL. To easily define
the threshold range, multiply the value of the resolution (lux/step) by the threshold level (refer to table 14).
•ALS Persistence
The ALS INT is triggered once the ALS value is higher or lower than the threshold window. The ALS_PERS (1, 2, 4, 8 times)
parameter, sets the amount of consecutive hits needed, in order for an interrupt event to trigger.
• Programmable PS Threshold
VCNL4040 provides both high and low thresholds setting for PS (register: PS_THDL, PS_THDH).
•PS Persistence
The PS persistence function (PS_PERS, 1, 2, 3, 4) helps to avoid false trigger of the PS INT. It defines the amount of
consecutive hits needed in order for a PS interrupt event to be triggered.
• PS Active Force mode
An extreme power saving way to use PS is to apply PS active force (register: PS_CONF3 command: PS_AF = 1) mode.
Anytime host would like to request one proximity measurement, write a ‘1’ into register: PS_CONF3 command: PS_Trig. This
triggers a single PS measurement, which can be read from the PS result registers. VCNL4040 stays in standby mode
constantly.
Data Access
All of VCNL4040 16 bit command registers are readable. The result data for ALS, white, and PS measurements can be read out
form their respective registers. Each result is made of 2 bytes.
Intelligent Cancellation
VCNL4040 provides an intelligent cancellation method to reduce cross talk phenomenon for the proximity sensor. The output
data will be subtracted by the value set in register: PS_CANC.
TABLE 14 - ALS RESOLUTION AND MAXIMUM DETECTION RANGE
ALS_IT SENSITIVITY
MAXIMUM DETECTION
RANGE
ALS_IT
(7 : 6)
INTEGRATION TIME
(typ.)
UNIT
(lux/step)
UNIT
(lux)
(0, 0) 80 ms 0.10 6553.5
(0, 1) 160 ms 0.05 3276.8
(1, 0) 320 ms 0.025 1638.4
(1, 1) 640 ms 0.0125 819.2
TABLE 15 - 16-BIT ALS DATA FORMAT
VCNL4040
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Register ALS_DataM ALS_DataL