ISL29034_14 Datasheet, PDF (11/15 Pages) Intersil Corporation – Integrated Digital Light Sensor

ISL29034
Integration Time ADC Resolution [B3:B2]
B2 and B3 determine the ADC’s resolution and 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 measurement. Table 7 lists the possible ADC
resolution. Only 16bit ADC resolution can reject better 50/60Hz
noise flickering light source.
.
TABLE 7. ADC RESOLUTION DATA WIDTH
B3
B2
NUMBER OF CLOCK CYCLES n-BIT ADC
0
0
2¹⁶ = 65,536
16
0
1
2¹² = 4,096
12
1
0
2⁸ = 256
8
1
1
2⁴ = 16
4
Integration Time
TABLE 8. INTEGRATION TIME OF n-BIT ADC
n # ADC BITS
INTEGRATION TIME (ms)
4
0.022
8
0.352
12
5.6
16
105
Data Registers (Addresses: 0x02 & 0x03)
TABLE 9. ADC REGISTER BITS
Reg.
REGISTER BITS
Addr
DFLT
NAME (Hex) B7 B6 B5 B4 B3 B2 B1 B0 (Hex)
DATA_LSB 0x02 D7 D6 D5 D4 D3 D2 D1 D0 0x00
DATA_MSB 0x03 D15 D14 D13 D12 D11 D10 D9 D8 0x00
The ISL29034 has two 8-bit read-only registers to hold the upper
and lower byte of the ADC value. The upper byte is accessed at
address 0x03 and the lower byte is accessed at address 0x02.
For 16-bit resolution, the data is from D0 to D15; for 12-bit
resolution, the data is from D0 to D11; for 8-bit resolution, the
data is from D0 to D7 and for 4-bit resolution, the data is from
D0 to D3. The registers are refreshed after every conversion
cycle. The default register value is 0x00 at power-on.
TABLE 10. ADC DATA REGISTERS
ADDRESS
(hex)
CONTENTS
0x02 D0 is LSB for 4-, 8-, 12- or 16-bit resolution; D3 is MSB for
4-bit resolution; D7 is MSB for 8-bit resolution
0x03 D15 is MSB for 16-bit resolution; D11 is MSB for 12-bit
resolution
ID Register (Address: 0x0F)
TABLE 11. ID REGISTER BITS
ADDR
NAME (Hex) B7
REGISTER BITS
B6 B5 B4 B3 B2 B1 B0
DFLT
ID 0x0F BOUT RESERVED 1 0 1 RESERVED 1x101xxx
The ID register has three different types of information.
RESERVED BITS [B2:B0] AND [B6]
All RESERVED bits on the ISL29034 are Intersil used bits only.
Bit0 to Bit2 and Bit6 are RESERVED bits where their value might
change without any notification to the user. It is advised when
using the identification bits to identify the device in a system the
software should mask the Bit0 to Bit2 and Bit6 to Bit7 to properly
identify the device.
DEVICE ID BITS [B5:B3]
The ISL29034 provides 3-bits to identify the device in a system.
These bits are located on register address 0x0F, Bit3 to Bit5. The
identification bit value for the ISL29034 is xx101xxx. The device
identification bits are read only bits. It is important to notice that
Bit7 is a status bit for brownout condition (BOUT).
BROWNOUT STATUS BIT TO BOUT [B7]
Bit7 on register address 0x0F is a status bit for brownout
condition (BOUT). The default value of this bit is “BOUT = 1”
during the initial power-up, which indicates the device may
possibly have gone through a brownout condition. Therefore, the
status bit should be reset to “BOUT = 0” by an I²C write command
during the initial configuration of the device.
The default register value is 0xA8 at power-on.
Applications Information
Figure 14 is a normalized spectral response of various type of
light sources for reference.
1.0
0.9
FLUORESCENT
0.8
0.7
0.6
HALOGEN
0.5
INCAND.
0.4
SUN
0.3
0.2
0.1
0
350
550
750
950
WAVELENGTH (nm)
FIGURE 14. NORMALIZED SPECTRAL RESPONSE OF LIGHT SOURCES
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FN8370.1
April 9, 2014