LX1977IDU MICROSEMI [Microsemi Corporation], LX1977IDU Datasheet - Page 11

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

Copyright © 2010
Rev. 1.0, 2010-03-25
ADC_CLK (bit 3, R / W): Selects the internal ADC clock speed when CLK_SEL (bit 7) of register 01h is 0
INT_FLAG (bit 2, R / W): Interrupt Status Report
OV (bit 0, R): Overflow Indicator.
TM
1
RANGE_SEL = 00b (0 ~ 500 lux)
Full Scale ADC Output Value
@ F
Note:
Note:
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
= 0, if D
= 1, 1 on this bit indicates that the D
OSC
ADC will continue to run regardless of the interrupt status unless it is stopped by setting START_ADC
bit to 0. Note that the ADC integration time is much longer than the interrupt response time. Data output
of the ADC that generated the interrupt must be read immediately as the next sampled data by the ADC
will write over the D
INT_ENA (bit 1, R / W): Interrupt Enable Bit
(1) When INT_ENA = 0, the INT pin function will be disabled. However, the INT_FLAG function
(2) When INT_ENA = 1, the INT pin will perform the normal interrupt function.
(3) When ALS_ENA = 0, the INT pin will be set to high regardless of its previous status.
reached the maximum range but not over.
selected range limit. Bigger range should be selected.
1
= 40.96kHz,
When clock speed is selected, the selectable integration time set will be determined automatically.
For example, when ADC_CLK = 1, the selectable integration time will be 25ms, 100ms, 200ms or
400ms. Please refer to Table 24 for details.
could still be used as software interrupt to monitor the ALS readings. The user can still set the
thresholds and read the INT_FLAG status periodically or when it is needed instead of reading the
ALS data and calculating. If the INT_FLAG = 1, then it means the ALS reading is outside the
boundaries. If this function is not needed, the user just simply ignores the INT_FLAG bit status.
COUNT
= 0, select clock speed to normal (40.96 kHz)
= 1, select clock speed to ¼ normal (10.24 kHz)
= 0, no interrupt or was cleared. This bit can be set to 1 or 0 by SMBus command. Setting zero
= 1, interrupt triggered. When this bit is 1 and INT_ENA = 1, the INT pin will be asserted low
= 0, Disable interrupt pin function
= 1, Enable interrupt pin function
Table 16: Maximum Count for Different T
Set ADC to continuous conversion mode and start conversion. ADC_FLAG indicates
conversion status, 0 means conversion is in process, 1 means previous conversion is done
and data is ready in register 07h and 08h. Actually, after the first conversion, this bit will be
always 1. Interrupt function applies to this mode.
Note: When this mode is set, the ADC_FLAG will be set to zero right away.
to this bit will set the INT pin to high regardless of the previous state. When it is set to zero,
the internal counter for INT_PERSIST_CTRL will be reset to 0.
and stay low until this bit is set to zero or INT_ENA = 0. Writing 1 to this bit will override
any internal setting and generate an interrupt if INT_ENA = 1. This function is useful for
testing user hardware and debugging software.
has reached the maximum value and this bit is still 0, it means that the input light has
COUNT
Analog Mixed Signal Group
D
D
COUNT
COUNT
register during continuous conversion mode.
®
Microsemi
COUNT
T
T
INT
INT
= 100 ms
= 50 ms
has reached the maximum value and the input light is over the
SMBus Ambient Light Sensor
P
INT
RODUCTION
Time
4095
2047
D
ATASHEET
Counts
LX1977
Page 11