
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.
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 I 2 C 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 I 2 C.
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 I 2 C devices on the bus.
The Si1141/42/43 I 2 C slave address is 0x5A. The Si1141/42/43 also responds to the global address (0x00) and the
global reset command (0x06). Only 7-bit I 2 C addressing is supported; 10-bit I 2 C addressing is not supported.
Conceptually, the I 2 C interface allows access to the Si1141/42/43 internal registers. Table 15 on page 28 is a
summary of these registers.
An I 2 C write access always begins with a start (or restart) condition. The first byte after the start condition is the I 2 C
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
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Rev. 1.3