APDS-9004 Datasheet, PDF (14/14 Pages) AVAGO TECHNOLOGIES LIMITED – Miniature Surface-Mount Ambient Light Photo Sensor

Appendix C: General Application Guide for APDS-9004
The APDS-9004 is a low cost analog-output ambient
light photo sensor whose spectral response closely
emulates the human eyes. APDS-9004 consists of a
phototransistor that enables the photo sensor to
produce a high gain photo current to a sufficient level
that can be converted to voltage with a standard value
of external resistor. APDS-9004 is then easily integrated
into systems that use ADC input which is available for
sampling of the external source, as shown in figure 7
below.
The amount of converted voltage, Vout, is mainly
dependant proportionally on the photo current which
generated by the brightness of the light shone on the
photo sensor and the load resistor used, RL. Increasing
the brightness of the light or/and the load resistor will
increase the output voltage.
Brightness is measured as “LUX” unit, which describes
how intense a light source that our eyes perceive. LUX
meter is the equipment for “LUX” measurement. Light
sources with the same LUX level appear at the same
brightness to the human eyes.
Vcc
2,3
Light Source
1
Vout
APDS-9004
A/D
4
C
RL
NC
micro-
controller
Figure 7. Configuration of APDS-9004 being used directly
Selection of the load resistor RL will determine the
amount of current-to-voltage conversion in the circuit.
Light source e.g. fluorescent light consists of ac noise
about 100Hz frequency. A capacitor of 10uF, which
acting as a low-pass filter, is recommended to add in
parallel with the load resistor to by-pass this ripples.
For product information and a complete list of distributors, please go to our web site: www.avagotech.com
Avago, Avago Technologies, and the A logo are trademarks of Avago Technologies, Limited in the United States and other countries.
Data subject to change. Copyright © 2006 Avago Technologies Pte. All rights reserved.
AV01-0184EN - September 14, 2006