ISL29147_15 Datasheet, PDF (13/15 Pages) Intersil Corporation – Low Power Ambient Light and Proximity Sensor with Enhanced Infrared Rejection

ISL29147
Soldering Considerations
Convection heating is recommended for reflow soldering;
direct-infrared heating is not recommended. The plastic optical
co-package does not require a custom reflow soldering profile. A
standard reflow soldering profile with a +260°C maximum is
recommended. Additional information regarding soldering the
ISL29147 is included in Intersil Technical Brief TB493.
PCB Layout Considerations
The ISL29147 is relatively insensitive to PCB layout. Adherence to
the following guidelines will ensure first pass success and best
performance.
Route the I²C/SMBus SCL, SDA and the INT traces away from
sources of switching noise.
The ISL29147 pin GND should connect to a low impedance
ground with low resistance and low inductance traces. Ferrite
beads and inductors should be avoided in the ground path. If
necessary, due to RF consideration, the effects of DCR
(DC resistance) should be evaluated on ALS and Proximity
system performance.
A 1µF ceramic decoupling capacitor should be placed as close to
VDD pin as possible.
The ISL29147 drives the IR LED with 0.09ms current pulses. To
supply this pulsed current, a 1 to 10µF bulk decoupling capacitor
(C₁) must be connected from the IR LED anode to the GND pin to
minimize instantaneous resistive voltage drop. The connection
from IR LED cathode to the IRDR pin should be short and with
minimal inductance. Similarly, connection from IR LED anode to
VDD_IRLED must be made with a low impedance trace.
For most applications, a single power supply may be used to
power the IR LED and the ISL29147. Use of resistor R₁ and
capacitor C₂ (Figure 11) to help filter out the power supply noise
generated from IR LED switching, is recommended for best
ISL29147 performance when using a single power supply. For
dual supply operation, resistor R₁ should not be installed.
Submit Document Feedback ₁₃
FN8409.3
January 6, 2015