|ISL29011IROZ-EVALZ||Digital Ambient Light Sensor and Proximity Sensor with Interrupt Function|
|ISL29011IROZ-EVALZ Datasheet PDF : 16 Pages |
conditions, the ADC can be configured at its lowest range
(Range 1) in the ambient light sensing. For very bright
conditions, the ADC can be configured at its highest range
(Range 4) in the proximity sensing.
The ISL29011 initial operation is at the power-down mode
after a supply voltage is provided. The data registers contain
the default value of 0. When the ISL29011 receives an I2C
command to do a one-time measurement from an I2C master,
it will start ADC conversion with light or proximity sensing. It
will go to the power-down mode automatically after one
conversion is finished and keep the conversion data available
for the master to fetch anytime afterwards. The ISL29011 will
continuously do ADC conversion with light or proximity
sensing if it receives an I2C command of continuous
measurement. It will continuously update the data registers
with the latest conversion data. It will go to the power-down
mode after it receives the I2C command of power-down.
Ambient Light, IR and Proximity Sensing
There are six operational modes in ISL29011: Programmable
ALS once with auto power-down, programmable IR sensing
once with auto power-down, programmable proximity sensing
once with auto power-down; programmable continuous ALS
sensing, programmable continuous IR sensing and
programmable continuous proximity sensing. These six
modes can be programmed in series to fulfill the application
needs. The detailed program configuration is listed in
“Register Set” on page 8.
When the part is programmed for ambient light sensing, the
ambient light with wavelength within the “Ambient Light
Sensing” spectral response curve in Figure 7 is converted
into current. With ADC, the current is converted to an
unsigned n-bit (up to 16 bits) digital output.
When the part is programmed for infrared (IR) sensing, the
IR light with wavelength within the “IR or Proximity Sensing”
spectral response curve on Figure 7 is converted into
current. With ADC, the current is converted to an unsigned
n-bit (up to 16 bits) digital output.
When the part is programmed for proximity sensing, the
external IR LED is turned on by the built-in IR LED driver
through the IRDR pin. The amplitude of the IR LED current
and the IR LED modulation frequency can be programmed
through Command Register II. When the IR from the LED
reaches an object and gets reflected back, the reflected IR
light with wavelength within the “IR or Proximity Sensing”
spectral response curve in Figure 7 is converted into current.
With ADC, the current is converted to an unsigned n-bit (up
to 16 bits) digital output. The output reading is inversely
proportional to the square of the distance between the
sensor and the object.
The active low interrupt pin is an open drain pull-down
configuration. There is also an interrupt bit in the I2C register.
The interrupt serves as an alarm or monitoring function to
determine whether the ambient light level or the proximity
detection level exceeds the upper threshold or goes below the
lower threshold. The user can also configure the persistency
of the interrupt. This reduces the possibility of false triggers,
such as noise or sudden spikes in ambient light conditions. An
unexpected camera flash, for example, can be ignored by
setting the persistency to 8 integration cycles.
There are eight 8-bit registers available inside the ISL29011.
The two command registers define the operation of the device.
The command registers do not change until the registers are
overwritten. The two 8-bit data Read Only registers are for the
ADC output and the Timer output. The data registers contain
the ADC's latest digital output, or the number of clock cycles in
the previous integration period. The four 8-bit interrupt registers
hold 16-bit interrupt high and low thresholds.
The ISL29011’s I2C interface slave address is internally
hard-wired as 1000100. When 1000100x with x as R or W is
sent after the Start condition, this device compares the first
seven bits of this byte to its address and matches.
Figure 2 shows a sample one-byte read. Figure 3 shows a
sample one-byte write. The I2C bus master always drives
the SCL (clock) line, while either the master or the slave can
drive the SDA (data) line. Figure 3 shows a sample write.
Every I2C transaction begins with the master asserting a
start condition (SDA falling while SCL remains high). The
following byte is driven by the master, and includes the slave
address and read/write bit. The receiving device is
responsible for pulling SDA low during the
acknowledgement period. Every I2C transaction ends with
the master asserting a stop condition (SDA rising while SCL
For more information about the I2C standard, please consult
the Philips™ I2C specification documents.
February 4, 2010
|Direct download click here|
|Share Link :|