LX1977IDU MICROSEMI [Microsemi Corporation], LX1977IDU Datasheet - Page 16

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

Low Threshold Register 02h, 03h (R / W)
High Threshold Register 04h, 05h (R / W)
Copyright © 2010
Rev. 1.0, 2010-03-25
Index Address = 00000010b, 00000011b or 02h, 03h
Access = Read / Write
Default = 00000000b, 00000000b
for the period of time set per INT_PERSIST_CTRL (register 01h bit 2, 1, 0), the INT_FLAG will be set to 1 and if the
INT_ENA is 1, the INT pin will be pulled low to indicate an interrupt on the INT pin.
D
INT_FLAG will be set and if INT_ENA = 1, the INT pin will be asserted low. If the INT_PERSIST_CTRL programmed
time period is not reached and a new D
counter for INT_PERSIST_CTRL will be reset to zero. If the INT_PERSIST_CTRL programmed time period is not reached
and a new D
COUNT
Read / Write
Read / Write
it will put register 01 data in the Data Byte field and send back to host. See Table 11 for details.
These two registers set the low threshold value of the interrupt function. If the ALS readout D
For example, if INT_ENA is set to 1 and INT_PERSIST_CTRL = 101 and the integration time is set to 100ms, and if the
Bit 7 to bit 4 in register 03h are always zero and can not be changed.
TM
Bit 7
Bit 7
N / A
N / A
7
7
0
7
7
0
value is lower than this register value for consecutive five times, i.e. 5 x 100 = 500ms, then an interrupt flag
1) Bit 7 will select the internal clock
2) Bit 6 & 5 will set detectable range to 0 ~ 500 lux
3) Bit 4, 3 will set the integration time or conversion time to either 50ms or 200ms depending on register 00h bit 3
4) Bit 2, 1 & 0 will set LX1977 to generate interrupt after D
Register 01h could be read back by the host by using Read Byte protocol. When LX1977 receives Read Byte protocol,
COUNT
setting. If bit 3 is 0, then the integration time is 50ms, otherwise it is 200ms
or below the low threshold for 5 consecutive times
Read / Write
Read / Write
value is greater than the High Threshold value, the counter starts over at ‘1’.
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Bit 6
Bit 6
N / A
N / A
0
0
6
6
6
6
Table 31: High Threshold Higher 4 bits Register 05h
Table 29: Low Threshold Higher 4 bits Register 03h
Table 30: High Threshold Lower Byte Register 04h
Table 28: Low Threshold Lower Byte Register 02h
Read / Write
Read / Write
Bit 5
Bit 5
N / A
N / A
5
5
0
5
5
0
COUNT
Analog Mixed Signal Group
value is between this Low Threshold value and the High Threshold value, the
Read / Write
Read / Write
®
Microsemi
Bit 4
Bit 4
N / A
N / A
4
4
0
4
4
0
Read / Write
Read / Write
Read / Write
Read / Write
Bit 11
Bit 11
Bit 3
Bit 3
3
3
3
3
SMBus Ambient Light Sensor
COUNT
P
is above the high threshold for 5 consecutive times
Read / Write
Read / Write
Read / Write
Read / Write
RODUCTION
Bit 10
Bit 10
Bit 2
Bit 2
2
2
2
2
D
Read / Write
Read / Write
Read / Write
Read / Write
ATASHEET
Bit 1
Bit 9
Bit 1
Bit 9
1
1
1
1
COUNT
is lower than this value
Read / Write
Read / Write
Read / Write
Read / Write
Bit 0
Bit 8
Bit 0
Bit 8
LX1977
0
0
0
0
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