Si1120-A-GM Silicon Laboratories Inc, Si1120-A-GM Datasheet - Page 7

• Manufacturer Part Number: Si1120-A-GM
• Description: Industrial Optical Sensors Proximity/Ambient Light Snsr w/PWM Out
• Manufacturer: Silicon Laboratories Inc
• Type: Ambient Light Sensor with Analog Outputr

Specifications of Si1120-A-GM

• Product: Integrated Ambient Light and Proximity Sensor
• Output Type: Analog - Voltage
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2.2. Mode Selection
The Si1120 features a shutdown mode, three proximity-detection modes, three ambient-light sensing modes, and
an offset calibration for high-sensitivity mode. Mode selection is accomplished through the sequencing of the SC
(shutdown/clock), MD (mode), and STX (strobe/transmit) pins.
The part enters shutdown mode unconditionally when SC is high. Each of the MD and STX inputs should be set to
a valid high or low state. In shutdown mode, the PRX output is tri-stated, and the power-supply and TXO output
leakage currents are negligible.
The active modes are set by clocking the state of MD and STX on the falling edge of SC and then setting MD to the
required state. Since setting SC high forces shutdown, SC must be held low for the selected mode to remain
active. The timing diagram in Figure 2 illustrates the programming sequence. Table 4 indicates the various mode
encodings. After the correct state has been programmed, the STX input is used to trigger measurements.
If the mode must be changed, the SC pin may need to be rearmed (set high), in which case the shutdown mode is
set and a power-on latency of about 500 µs is incurred upon enabling of the selected mode when SC goes back
low. Following a mode change, STX must be kept low during the power-up latency period. If the host sets STX too
early, the Si1120 may not begin a measurement cycle; PRX does not assert. If this occurs, the host can restart a
measurement by toggling STX.
Mode
PRX400
OFC
PRX50
PRX50H
VIRL
VAMB
VIRH
(Reserved) Reserved mode
Proximity, 50 mA LED current (Mode 2)
Proximity, 400 mA LED current (Mode 0)
Offset calibration for high sensitivity (Mode 1)
Proximity, 50 mA LED current, high reflectance (Mode 3)
Visible and infrared ambient, low range (Mode 4)
Visible ambient (Mode 5)
Visible and infrared ambient, high range (Mode 6)
Figure 2. Si1120 Mode Programming Timing Diagram
Description
Table 4. Mode Control Table
Rev. 1.0
STX (Latch) MD (Latch) MD (Static)
0
0
0
0
1
1
1
1
1
0
1
0
0
1
0
1
Si1120
0
1
0
1
0
1
0
1
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