TSL2671 datasheet(21/27 Pages) AMSCO

21 / 27 page

TSL2671

DIGITAL PROXIMITY DETECTOR

TAOS118 − JANUARY 2011

E 2011, TAOS Inc.

The LUMENOLOGY

r Company

www.taosinc.com

APPLICATION INFORMATION: HARDWARE

LED Driver Pin with Proximity Detection

The application hardware circuit with proximity detection requires an LED connected as shown in Figure 14.

Vbat may be an independent power source. The 1-μF decoupling capacitors should be of the low-ESR type and

be placed as close as possible to the load and VDD to reduce noise. To maximize system performance, the use

of PCB power and ground planes are recommended. If mounted on a flexible circuit, the power and ground

traces back to the PCB should be sufficiently wide enough to have a low resistance, such as < 1

Ω.

The I2C bus protocol was developed by Philips (now NXP). The pull-up resistor value (RP) is a function of the

I2C bus speed, the supply voltage, and the capacitive bus loading. Users should consult the NXP I2C design

specification (http://www.i2c−bus.org/references/) for assistance. With a lightly loaded bus running at 400 kbps

and VDD = 3 V, 1.5-kΩ resistors have been found to be viable.

TSL2671

VBUS

VDD(digital)

SCL

SDA

RPI

INT

LDR

LED

VDD(analog)

Figure 14. Application Hardware Circuit for Proximity Sensing with Internal LED Driver

The power supply connection — PCB routing and supply decoupling — has a significant effect on proximity

performance. Contact TAOS or see the application notes available at www.TAOSinc.com for power supply

guidance.

TSL2671 Folha de dados(PDF) 21 Page - ams AG