VCNL4100 Datasheet, PDF (7/17 Pages) Vishay Siliconix – High Sensitivity Long Distance Proximity and Ambient Light Sensor with I2C Interface

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VCNL4100
Vishay Semiconductors
APPLICATION INFORMATION
Pin Connection with the Host
VCNL4100 is a cost effective solution of a long distance proximity sensor with I²C interface. The standard serial digital interface
easily accesses “light intensity” by using simple calculations.
Application circuitry below shows the added MOSFET which is driven by the ASIC’s pin 2. A 22 k pull-up resistor needs to be
added here. The R_LED defines the current through the IRED. A small 0.1 μF is sufficient at V_DD for power supply noise rejection,
but a 2.2 μF should be placed at V_IRED to provide the energy for the IRED.
For the I²C bus design, the pull-up voltage refers to the I/O specification of the baseband due to its “open drain” design. The
pull-high resistors for the I²C bus lines are recommended to be  2.2 k.
V_{pull up}
V_DD
0.1 μF
V_IRED
2.2 μF
2.2 kΩ
SCK
SDA
MCU
INT
2.2 kΩ
10
SSCCLLKK
9
SDAT
3
20 kΩ
V_DD
LED ₂
CATHODE
S
G
D
PMOS
8.2 kΩ
VCNL4100
8 _IINNTT
LED+ ⁶
LED- ⁵
GND
1
R_LED
2.7 Ω
Fig. 10 - Application Diagram
Notes
• V_DD range: 2.5 V to 3.6 V and V_IRED is recommended 5.0 V
• Power path of V_DD and V_IRED should be routed separately up to stable power source.
• The R_LED resister value should be evaluated within ready-made application and the current through VCNL4100-internal IRED should not
exceed 800 mA.
Digital Interface
VCNL4100 applies single 8-bit slave address 0xC0 (HEX) following I²C protocol. All operations can be controlled by the
command register. The simple command structure helps users easily program the operation setting and latch the light data from
VCNL4100. As fig. 11 shows, VCNL4100’s I²C command format is simple for read and write operations between VCNL4100
and the host. The white sections indicate host activity and the gray sections indicate VCNL4100’s acknowledgement of the host
access activity. Write word and read word protocols are suitable for accessing registers particularly for 16-bit ALS data and
8-bit PS data. Interrupt can be cleared by reading data out from register: INT_Flag.
Send Byte ɦ Write Command to VCNL4100
1
7
1
1
8
1
8
1
8
1
1
S
Slave Address
Wr A
Command Code
A
Data Byte Low
A
Data Byte High
AP
Receive Byte ɦ Read Data from VCNL4100
1
7
1
1
8
1
1
7
1
1
8
1
8
1
1
S
Slave Address
Wr A
Command Code
AS
Slave Address
Rd A
Data Byte Low
A
Data Byte High
AP
S = start condition
P = stop condition
A = acknowledge
Shaded area = VCNL4100 acknowledge
Fig. 11 - Command Protocol Format
Rev. 1.2, 30-Aug-16
7
Document Number: 84319
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