ISL29002 Datasheet, PDF (6/10 Pages) Intersil Corporation – Light-to-Digital I2C Sensor

ISL29002
Command Register
The command register is used to define the ADC's
operations. Table 1 shows the primary commands used to
control the ADC.
Note that there are two classes of operating commands:
three for internal timing, and three for external (arbitrary)
timing.
When using any of the three external timing commands,
each command received by the device ends one conversion
and begins another. The integration time of the device is
thus the time between one I²C external timing command and
the next. The integration time can be between 1ms and
100ms. The external timing commands can be used to
synchronize the ADC’s integrating time to a PWM dimming
frequency in a backlight system in order to eliminate noise.
When using any of the three internal timing commands, the
device self-times each conversion, which is nominally 110ms
(with R_EXT = 100kΩ).
TABLE 1. COMMAND REGISTERS AND FUNCTIONS
COMMAND
FUNCTION
8C(hex)
ADC is powered-down. To enable ADC from a powered-down state, send any command to the ISL29002.
0C(hex)
ADC is reset. A reset restarts the counter value to zero and returns the clock cycle to zero.
00(hex)
04(hex)
08(hex)
30(hex)
34(hex)
38(hex)
1xxx_xxxx
(binary)
Internal Timing Mode. Integration
time is 110ms per photodiode.
ADC converts Diode 1’s current (I_DIODE1) into an unsigned-magnitude 16-bit data.
ADC converts Diode 2’s current (I_DIODE2) into unsigned-magnitude 16-bit data.
ADC converts I_DIODE1-I_DIODE2 into 2’s-complement 16-bit data.
External Timing Mode. Each external ADC converts Diode 1’s current (I_DIODE1) into unsigned-magnitude 16-bit data.
timing command sent to the device
ends one integration period and
ADC converts Diode 2’s current (I_DIODE1) into unsigned-magnitude 16-bit data.
begins another.
ADC converts I_DIODE1-I_DIODE2 into 2’s-complement 16-bit data.
I²C communication test. The value written to the command register can be read
back via the I²C bus.
I²C DATA
I²C SDA In
Start
DEVICE ADDRESS 40(h) to 47(h)
WA
POWER DOWN CMD 8C(h)
A
STOP
A6 A5 A4 A3 A2 A1 A0 W A R7 R6 R5 R4 R3 R2 R1 R0 A
I²C SDA Out
SDA DRIVEN BY MASTER
A
SDA DRIVEN BY MASTER
A
I²C CLK In
123456789123456789
FIGURE 11A. I²C WRITE TIMING DIAGRAM SAMPLE
I²C DATA
I²C SDA In
Start
DEVICE ADDRESS 44(HEX) R/W A
LSB OF SENSOR READING
A
MSB OF SENSOR READING
STOP
A6 A5 A4 A3 A2 A1 A0 R A
SDA DRIVEN BY ISL29002
A
SDA DRIVEN BY ISL29002
A
I²C SDA Out
SDA DRIVEN BY MASTER
A D7 D6 D5 D4 D3 D2 D1 D0 A D7 D6 D5 D4 D3 D2 D1 D0 A
I²C CLK In
123456789123456789123456789
FIGURE 11B. I²C READ TIMING DIAGRAM SAMPLE
FIGURE 11.
6
FN7465.2
December 1, 2006