MAX44007 Maxim, MAX44007 Datasheet - Page 13

• Manufacturer Part Number: MAX44007
• Description: The MAX44007 ambient light sensor features an I²C digital output that is ideal for a number of portable applications such as smartphones, notebooks, and industrial sensors
• Manufacturer: Maxim

The count is multiplied by 0.025, which is the LSB.
Because of the logarithmic nature of autoranging cir-
cuitry implemented on the IC, resolution of ambient lux
readings scale with the absolute measurement. Table 8
lists the lux resolution and the lux ranges obtained from
the IC.
Interrupt is enabled by setting bit 0 of register 0x01 to
1 (see Table 1). INT, an open-drain output, pulls low
when an interrupt condition occurs (lux readings that
exceed threshold limits for a period greater than that set
by the Threshold Timer register). The interrupt status bit
is cleared automatically if register 0x00 is read or if the
interrupt is disabled (INTE = 0).
The IC’s interrupt circuit requires the upper and lower
limit thresholds to be in a specific format to be properly
interpreted. The upper and lower limits, from registers
0x05 and 0x06 must match the lux high-byte format. This
consists of the 4 bits of the exponent and the 4 most sig-
nificant bits of the mantissa (E3 E2 E1 E0 M7 M6 M5 M4).
In this case, there is the following formula:
Lower lux threshold = (2
The exponent is a 4-bit number ranging from 0000 to
1110 (zero to 14).
Table 8. Lux per LSB in Automatic Mode
LUX (MIN)
13,107.2
26,214.4
52,428.8
1638.4
3276.8
6553.6
102.4
204.8
409.6
819.2
12.8
25.6
51.2
6.4
0
Threshold Register Data Format
Low-Power Digital Ambient Light Sensor
(exponent)
LUX (MAX)
104,448.0
13,107.2
26,214.9
54,428.8
1638.4
3276.8
6553.6
102.4
204.8
409.6
819.2
12.8
25.6
51.2
Interrupt Settings
x mantissa) x 0.025
6.4
AUTOMATIC MODE
LUX PER LSB IN
with Enhanced Sensitivity
0.025
102.4
204.8
409.6
0.05
12.8
25.6
51.2
0.1
0.2
0.4
0.8
1.6
3.2
6.4
The mantissa is an 8-bit number ranging from 0000 0000
to 1111 0000 (zero to 240).
Upper lux threshold = (2
The exponent is a 4-bit number ranging from 0000 to
1110 (zero to 14).
The mantissa is an 8-bit number ranging from 0000 1111
to 1111 1111 (15 to 255).
In the auto range mode (MANUAL = 0), the upper thresh-
old and lower threshold bytes must be in a format that
matches the format used in register 0x03, the lux high
byte. There are only two rules to follow:
• For very low lux levels (light levels below 6.4 lux),
• For all other conditions (light levels above 6.4 lux)
In manual mode (MANUAL = 1), Table 9 gives the range
of exponent (E3 E2 E1 E0) that can be used for each
TIM[2:0] and CDR bit setting.
set the exponent to zero, the code is merely: 0000
MMMM where the 4 zeroes are the exponent, and the
MMMM represent the 4 most significant bits of the
mantissa.
where the exponent is not zero, the format is: EEEE
1MMM. Notice that bit M7 (most significant bit) must
always be a 1. The other bits do not matter. EEEE is
limited to a maximum value of 1110. The maximum
usable setting is a code of 1110 1111.
COUNTS (MIN)
1,048,576
2,097,152
131,072
262,144
524,288
16,384
32,768
65,536
1024
2048
4096
8192
256
512
0
(exponent)
x mantissa) x 0.025
COUNTS (MAX)
1,048,576
2,097,152
4,177,920
131,072
262,144
524,288
16,384
32,768
65,536
1024
2048
4096
8192
256
512
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