LX1977IDU MICROSEMI [Microsemi Corporation], LX1977IDU Datasheet - Page 13

• Manufacturer Part Number: LX1977IDU
• Description: SMBus Ambient Light Sensor
• Manufacturer: MICROSEMI [Microsemi Corporation]

Copyright © 2010
Rev. 1.0, 2010-03-25
Device Control Register 01h (R / W)
Index Address = 00000001b or 01h
Access = Read / Write
Default = 00000000b
Bit Definitions:
Read / Write
CLK_SEL
device settings.
CLK_SEL (bit 7, R / W): Selects the source of the ADC clock
RANGE_SEL (bit 6, 5, R / W): Selects the detectable input light range.
TM
7
This protocol will send commands to LX1977 and will write the command byte into register 00h for configuring the
1) Bit 6 will enable LX1977 ALS function
2) Bit 5, 4 will set ADC mode to Continuous Conversion Mode and start ADC
3) Bit 3 will select 40.96 kHz clock frequency as the Sigma-Delta ADC clock
4) Bit 2 will clear the interrupt flag no matter what it was
5) Bit 1 will enable the interrupt function
6) Bit 0 will be ignored since bit 0 of register 00h is a read only bit
Bit 6 Bit 5
Bit 6 Bit 5
0
0
1
1
0
0
1
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Table 22: ADC T
Table 23: ADC T
6
RANGE_SEL
0
1
0
1
0
1
0
Read / Write
Range (lux)
Range (lux)
Full Scale
Full Scale
= 0, use internal clock (the actual speed will depend on bit 3 of register 00h setting)
= 1, use SMBus host SCL clock. Since the clock gap between protocols is inconsistent, this
0 ~ 1000
0 ~ 5000
0 ~ 2500
0 ~ 1000
0 ~ 5000
0 ~ 500
0 ~ 500
mode is not
5
INT
INT
Table 21: Control Register 01h
, Range and Resolution @ ADC Clock = 40.96 kHz
, Range and Resolution @ ADC Clock = 10.24 kHz
T
D
D
T
INT
Analog Mixed Signal Group
recommended.
COUNT
COUNT
INT
21.46
10.73
21.46
= 6.25 ms
2.15
4.29
2.15
4.29
= 25 ms
®
Microsemi
= 233
= 233
4
Read / Write
T
INT
Resolution in Lux /Count
Resolution in Lux /Count
T
_SET
D
D
T
INT
INT
COUNT
COUNT
0.54
1.07
5.37
2.68
= 100 ms
0.54
1.07
5.37
= 25 ms
= 931
= 931
3
SMBus Ambient Light Sensor
D
D
T
T
P
COUNT
COUNT
INT
INT
RODUCTION
0.27
0.54
2.69
1.34
0.27
0.54
2.69
= 200 ms
= 50 ms
= 1861
= 1861
2
INT_PERSIST_SET
D
D
T
T
D
COUNT
COUNT
INT
INT
Read / Write
ATASHEET
0.13
0.27
1.34
0.67
0.13
0.27
1.34
= 100 ms
= 400 ms
= 3723
= 3723
1
LX1977
0
Page 13