SI1143 View Datasheet(PDF) - Silicon Laboratories

Part Name

Description

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SI1143

PROXIMITY/AMBIENT LIGHT SENSOR IC WITH I2C INTERFACE

Silicon Laboratories 

Si1141/42/43

The window can be applied to either the Visible Ambient Measurement, or the Infrared Ambient Measurement, but

not both. However, monitoring the ambient change in either channel should allow notification that the ambient light

level has changed.

NormalizedPhotodiodeResponse

1

0.9

VIS

IR

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

250

350

450

550

650

750

850

950

1050

Wavelength(nm)

Figure 7. Photodiode Spectral Response to Visible and Infrared Light (Indicative)

2.4. Host Interface

The host interface to the Si1141/42/43 consists of three pins:

 SCL

 SDA

 INT

SCL and SDA are standard open-drain pins as required for I2C operation.

The Si1141/42/43 asserts the INT pin to interrupt the host processor. The INT pin is an open-drain output. A pull-up

resistor is needed for proper operation. As an open-drain output, it can be shared with other open-drain interrupt

sources in the system.

For proper operation, the Si1141/42/43 is expected to fully complete its Initialization Mode prior to any activity on

the I2C.

The INT, SCL, and SDA pins are designed so that it is possible for the Si1141/42/43 to enter the Off Mode by

software command without interfering with normal operation of other I2C devices on the bus.

The Si1141/42/43 I2C slave address is 0x5A. The Si1141/42/43 also responds to the global address (0x00) and the

global reset command (0x06). Only 7-bit I2C addressing is supported; 10-bit I2C addressing is not supported.

Conceptually, the I2C interface allows access to the Si1141/42/43 internal registers. Table 15 on page 29 is a

summary of these registers.

An I2C write access always begins with a start (or restart) condition. The first byte after the start condition is the I2C

address and a read-write bit. The second byte specifies the starting address of the Si1141/42/43 internal register.

Subsequent bytes are written to the Si1141/42/43 internal register sequentially until a stop condition is

encountered. An I2C write access with only two bytes is typically used to set up the Si1141/42/43 internal address

in preparation for an I2C read.

The I2C read access, like the I2C write access, begins with a start or restart condition. In an I2C read, the I2C

master then continues to clock SCK to allow the Si1141/42/43 to drive the I2C with the internal register contents.

14

Rev. 1.4

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