ISL29003_07 Datasheet, PDF (6/15 Pages) Intersil Corporation – Light-to-Digital Output Sensor with High Sensitivity, Gain Selection, Interrupt Function and I2C Interface

ISL29003
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TABLE 2. WRITE ONLY REGISTERS
REGISTER
ADDRESS
NAME
FUNCTIONS/
DESCRIPTION
b1xxx_xxxx
sync_iic
Writing a logic 1 to this address bit
ends the current adc-integration and
starts another. Used only with
External Timing Mode.
bx1xx_xxxx
clar_int
Writing a logic 1 to this address bit
clears the interrupt.
Command Register 00(hex)
The Read/Write command register has five functions:
(1) Enable; Bit 7. This function either resets the ADC or
enables the ADC in normal operation. A logic 0 disables
ADC to reset-mode. A logic 1 enables adc to normal
operation.
TABLE 3. ENABLE
BIT 7
OPERATION
0
disable ADC-core to reset-mode (default)
1
enable ADC-core to normal operation
(2) ADCPD; Bit 6. This function puts the device in a power
down mode. A logic 0 puts the device in normal operation. A
logic 1 powers down the device.
TABLE 4. ADCPD
BIT 6
OPERATION
0
Normal operation (default)
1
Power Down
(3) Timing Mode; Bit 5. This function determines whether the
integration time is done internally or externally. In Internal
Timing Mode, integration time is determined by an internal
dual speed oscillator (f_OSC), and the n-bit (n = 4, 8, 12,16)
counter inside the ADC. In External Timing Mode, integration
time is determined by the time between two consecutive
external-sync sync_iic pulse commands.
TABLE 5. TIMING MODE
BIT 5
OPERATION
0
Internal Timing Mode. Integration time is internally
timed determined by f_OSC, REXT, and number of
clock cycles.
1
External Timing Mode. Integration time is externally
timed by the I²C host.
(4) Photodiode Select Mode; Bits 3 and 2. This function
controls the mux attached to the two photodiodes. At Mode1,
the mux directs the current of Diode1 to the ADC. At Mode2,
the mux directs the current of Diode2 only to the ADC.
Mode3 is a sequential Mode1 and Mode2 with an internal
subtract function (Diode1 - Diode2).
TABLE 6. PHOTODIODE SELECT MODE; BITS 2 AND 3
BITS 3:2
MODE
0:0
MODE1. ADC integrates or converts Diode1 only.
Current is converted to an n-bit unsigned data.*
0:1
MODE2. ADC integrates or coverts Diode2 only.
Current is converted to an n-bit unsigned data.*
1:0
MODE3. A sequential MODE1 then MODE2
operation. The difference current is an (n-1) signed
data.*
1:1
No operation.
*n = 4, 8, 12,16 depending on the number of clock cycles
function.
(5) Width; Bits 1 and 0. This function determines the number
of clock cycles per conversion. Changing the number of
clock cycles does more than just change the resolution of
the device. It also changes the integration time, which is the
period the device’s analog-to-digital (A/D) converter samples
the photodiode current signal for a lux measurement.
BITS 1:0
0:0
0:1
1:0
1:1
TABLE 7. WIDTH
NUMBER OF CLOCK CYCLES
2¹⁶ = 65,536
2¹² = 4,096
2⁸ = 256
2⁴ = 16
Control Register 01(hex)
The Read/Write control register has three functions:
(1) Interrupt flag; Bit 5. This is the status bit of the interrupt.
The bit is set to logic high when the interrupt thresholds have
been triggered, and logic low when not yet triggered. Writing
a logic low clears/resets the status bit.
BIT 5
0
1
TABLE 8. INTERRUPT FLAG
OPERATION
Interrupt is cleared or not triggered yet
Interrupt is triggered
(2) Range/Gain; Bits 3 and 2. The Full Scale Range can be
adjusted by an external resistor Rext and/or it can be
adjusted via I²C using the Gain/Range function. Gain/Range
has four possible values, Range(k) where k is 1 through 4.
Table 9 lists the possible values of Range(k) and the
resulting FSR for some typical value R_EXT resistors.
6
FN7464.3
October 8, 2007