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OPT3007

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SBOS864 – AUGUST 2017

Product Folder Links: OPT3007

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Copyright © 2017, Texas Instruments Incorporated

7.3 Feature Description

7.3.1 Human Eye Matching

The OPT3007 spectral response closely matches that of the human eye. If the ambient light sensor

measurement is used to help create a good human experience, or create optical conditions that are optimal for a

human, the sensor must measure the same spectrum of light that a human sees.

The device also has excellent infrared light (IR) rejection. This IR rejection is especially important because many

real-world lighting sources have significant infrared content that humans do not see. If the sensor measures

infrared light that the human eye does not see, then a true human experience is not accurately represented.

Furthermore, if the ambient light sensor is hidden underneath a dark window (such that the end-product user

cannot see the sensor) the infrared rejection of the OPT3007 becomes significantly more important because

many dark windows attenuate visible light but transmit infrared light. This attenuation of visible light and lack of

attenuation of IR light amplifies the ratio of the infrared light to visible light that illuminates the sensor. Results

can still be well matched to the human eye under this condition because of the high infrared rejection of the

OPT3007.

7.3.2 Automatic Full-Scale Range Setting

The OPT3007 has an automatic full-scale range setting feature that eliminates the need to predict and set the

optimal range for the device. In this mode, the OPT3007 automatically selects the optimal full-scale range for the

given lighting condition. The OPT3007 has a high degree of result matching between the full-scale range

settings. This matching eliminates the problem of varying results or the need for range-specific, user-calibrated

gain factors when different full-scale ranges are chosen. For further details, see the Automatic Full-Scale Setting

Mode section.

example with the SMBus protocol specified only when a difference between the two protocols is discussed.

The OPT3007 is connected to the bus with two pins: an SCL clock input pin and an SDA open-drain bidirectional

data pin. The bus must be controlled by a master device that generates the serial clock (SCL), controls the bus

access, and generates start and stop conditions. To address a specific device, the master initiates a start

condition by pulling the data signal line (SDA) from a high logic level to a low logic level while SCL is high. All

slaves on the bus shift in the slave address byte on the SCL rising edge, with the last bit indicating whether a

read or write operation is intended. During the ninth clock pulse, the slave being addressed responds to the

master by generating an acknowledge bit by pulling SDA low.

Data transfer is then initiated and eight bits of data are sent, followed by an acknowledge bit. During data

transfer, SDA must remain stable while SCL is high. Any change in SDA while SCL is high is interpreted as a

start or stop condition. When all data are transferred, the master generates a stop condition, indicated by pulling

locking up the bus. If the SCL line is held low for this duration of time, the bus state machine is reset.

7.3.3.1 Serial Bus Address

address slave devices via a slave address byte. The slave address byte consists of a seven bit address 1000101

and a direction bit that indicates whether the action is to be a read or write operation.

7.3.3.2 Serial Interface

the SCL clock input line and the SDA open-drain I/O line. The OPT3007 supports the transmission protocol for

standard mode (up to 100 kHz), fast mode (up to 400 kHz), and high-speed mode (up to 2.6 MHz). All data bytes

are transmitted most-significant bits first.

The SDA and SCL pins feature integrated spike-suppression filters and Schmitt triggers to minimize the effects of