MAX44000 Maxim, MAX44000 Datasheet - Page 9

• Manufacturer Part Number: MAX44000
• Description: MAX44000 combines a wide-dynamic range ambient light sensor with an integrated infrared proximity sensor, making it a perfect solution for touch-screen portable devices
• Manufacturer: Maxim

The proximity sensing uses an external, pulsed infrared
LED source to emit controlled amounts of infrared radia-
tion. When an external object reflects back some of this
infrared radiation back to the IC, it is detected by the
integrated light detector. The amount of reflected light
detected is then used to determine the object’s proximity
to the sensor.
It is important to take account for the fact that different
objects at the same distance from the sensor can reflect
different amounts of infrared radiation depending on
their texture and color.
The IC includes on-chip ambient cancellation circuitry
in the receive path of the infrared proximity sensor. This
scheme allows the part to operate in the presence of
STATUS
Interrupt Status
CONFIGURATION
Main Configuration
Receive Configuration
Transmit Configuration
ADC DATA
ADC High Byte (ALS
ADC Low Byte (ALS
ADC Byte (PROX)
THRESHOLD SET
ALS Upper Threshold
(High Byte
ALS Upper Threshold
(Low Byte)
ALS Lower Threshold
(High Byte)
ALS Lower Threshold
(Low Byte)
REGISTER
)
Proximity Light Sensing
_______________________________________________________________________________________
)
)
Ambient and Infrared Proximity Sensor
B7
1
OFL
B6
1
TRIM
B5
1
B4
1
PRXDATA[7:0]
ALSDATA[7:0]
UPTHR[7:0]
LOTHR[7:0]
MODE[2:0]
B3
ALSTIM[1:0]
ALSDATA[13:8]
UPTHR[13:8]
LOTHR[13:8]
PWRON PRXINTS ALSINTS
large amounts of DC IR radiation. Due to the use of a
single-pulse technique in pulsing the external infrared
LED, the chip is also immune to fixed-frequency external
infrared radiation such as from remote controls, elec-
tronic ballasts, etc., leading to more reliable infrared
proximity sensor operation.
The IC features a LED driver that delivers a pulsed cur-
rent at the output. The pulse amplitude is programmable
through the I
10mA. A low-voltage compliance of DRV pin allows IR
LEDs to be powered from lower voltage rails, possibly
even a 1.8V rail. High-current drive accuracy improves
performance by eliminating part-to-part variation.
B2
DRV[3:0]
PRXINTE ALSINTE
B1
ALSPGA[1:0]
2
C interface from 0 to 110mA in steps of
B0
Register Description
REGISTER
ADDRESS
0x00
0x01
0x02
0x03
0x04
0x05
0x16
0x06
0x07
0x08
0x09
POWER-ON
LED Driver
RESET
STATE
0x04
0x24
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
R
R
R
9