Document Number: 83798

www.vishay.com

Rev. 1.5, 12-May-11

9

This document is subject to change without notice.

VCNL4000

Fully Integrated Proximity and Ambient Light Sensor

Vishay Semiconductors

Register #10 Proximity Modulator Timing Adjustment

Register address = 8Ah.

Note

• The settings for best performance will be provided by Vishay. With first samples this is evaluated to: delay time = 4 and dead time = 1, with

that register #10 should be programmed with: 129 (dez.)

Register #11 Ambient IR Light Level Register

Register address = 8Bh.

This register is not intended to be used by customer.

3. IMPORTANT APPLICATION HINTS AND EXAMPLES

3.1 Receiver standby mode

This is always valid, when there are no measurement demands for proximity and ambient light executed. Also the current sink

for the IR-LED is inactive, so there is no need for changing register #3 (IR LED current).

3.2 Data Read

In order to get a certain register value, the register has to be addressed without data like shown in the following scheme. After

this register addressing, the data from the addressed register is written after a subsequent read command.

Fig. 14 - Send Byte/Receive Byte Protocol

The stop condition between these write and read sequences is not mandatory. It works also with a repeated start condition.

Note

• For reading out 2 (or more) subsequent registers like the result registers, it is not necessary to address each of the registers separately. After

one read command the internal register counter is increased automatically and any subsequent read command is accessing the next

register.

Example: read register “Ambient Light Result Register” #5 and #6:

TABLE 10 - PROXIMITY MODULATOR TIMING ADJUSTMENT #10

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Modulation delay time

N/A

Modulation dead Time

Description

Modulation delay time

R/W bits. Setting a delay time between IR LED signal and IR input signal evaluation.

This function is for compensation of delays from IR LED and IR photo diode.

Also in respect to the possibility for setting different proximity signal frequency.

Correct adjustment is optimizing measurement signal level.

Modulation dead Time

R/W bits. Setting a dead time in evaluation of IR signal at the slopes of the IR signal.

This function is for reducing of possible disturbance effects.

This function is reducing signal level and should be used carefully.

S

Slave address

Rd

Receive byte

Read data from VCNL4000

ARegister address

A

Wr

P

S

Slave address

P

A

A

Data byte

S = start condition

P = stop condition

A = acknowledge

Host action

VCNL4000 response

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