ISL29006, ISL29007, ISL29008
resistor at the output. This limit is set by the design of the
internal metal interconnects.
ISL29008 has the capability of both sourcing and sinking
current simultaneously. It may replace ISL29006 in sourcing
current applications, or ISL29007 in sinking current
applications. In applications that require both sourcing and
sinking currents, for example in cases of mobile phones or
PDAs where the display brightness needs to be proportional
to ambient brightness while the key pads need to be
inversely proportional to the brightness, ISL29008 offers the
most economical solution for cost and footprint.
Suggested PCB Footprint
Footprint pads should be a nominal 1-to-1 correspondence
with package pads. Since ambient light sensor devices do
not dissipate high power, heat dissipation through the
exposed pad is not important; instead, similar to DFN or
QFN, the exposed pad provides robustness in the board
mounting process. Therefore, we recommend that the
exposed pad be soldered down for robust joint formation, but
this is not mandatory.
Power Supply Bypassing and Printed Circuit
The ISL29006, ISL29007 and ISL29008 are relatively
insensitive to the printed circuit board layout due to their low
speed operation. Nevertheless, good printed circuit board
layout is necessary for optimum performance. Ground plane
construction is highly recommended; lead length should be
as short as possible and the power supply pins must be well
bypassed to reduce the risk of oscillation. For normal single
supply operation where the GND pin is connected to ground,
a 0.1µF ceramic capacitor should be placed from the VCC
pin to the GND pin. A 4.7µF tantalum capacitor should then
be connected in parallel, placed close to the device.
Optical Sensor Location Outline
The green area in Figure 22 shows the optical sensor
location outline of ISL29006, ISL29007 and ISL29008.
Along the pin-out direction, the center line (CL) of the sensor
coincides with that of the packaging. The sensor width in this
direction is 0.39mm. Perpendicular to the pin-out direction,
the CL of the sensor has a 0.19mm offset from the CL of
packaging away from pin-1. The sensor width in this
direction is 0.46mm.
ISL29006 LIGHT SENSOR
FIGURE 21. AUTOMATIC DIMMING CONTROL
September 21, 2010