VCNL4040

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Vishay Semiconductors

Rev. 1.7, 04-Nov-2020

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 I2C 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