ISL29018 View Datasheet(PDF) - Intersil
Part Name
Description
Manufacturer
ISL29018 Datasheet PDF : 15 Pages
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ISL29018
needs. The detailed program configuration is listed in
“Register Set” on page 7.
When the part is programmed for ambient light sensing, the
ambient light with wavelength within the “Ambient Light
Sensing” spectral response curve in Figure 6 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 6 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 6 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.
Interrupt Function
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.
I2C Interface
There are eight 8-bit registers available inside the ISL29018.
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 ISL29018’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 1 shows a sample one-byte read. Figure 2 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 2 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
remains high).
For more information about the I2C standard, please consult
the Philips™ I2C specification documents.
I2C DATA START
DEVICE ADDRESS W A REGISTER ADDRESS
STOP START DEVICE ADDRESS
A
DATA BYTE0
I2C SDA
IN
I2C SDA
OUT
A6 A5 A4 A3 A2 A1 A0 W A R7 R6 R5 R4 R3 R2 R1 R0 A
SDA DRIVEN BY MASTER
A SDA DRIVEN BY MASTER A
A6 A5 A4 A3 A2 A1 A0 W A
SDA DRIVEN BY ISL29018
SDA DRIVEN BY MASTER
A D7 D6 D5 D4 D3 D2 D1 D0
I2C CLK
12 3456 789123456 789
123 45 67 89123456789
FIGURE 1. I2C READ TIMING DIAGRAM SAMPLE
6
FN6619.1
February 11, 2010
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