8.1 I
2
C Interface
When in I
2
C mode, the serial interface operates in slave mode with 7-bit addressing and can operate in Standard-Mode (100 kbps)
or Fast-Mode (400 kbps) and supports burst data transfer with auto address increments. The I
2
C bus consists of a bidirectional serial
data line (SDA) and a serial clock input (SCL) as shown in Figure 8.12 SPI “Burst Data Write” Instruction Timing on page 43. Both the
SDA and SCL pins must be connected to a supply via an external pull-up (1k to 4.7k ohm) as recommended by the I
2
C specification
as shown in the figure below. Two address select bits (A0, A1) are provided allowing up to four Si5341/40 devices to communicate on
the same bus. This also allows four choices in the I
2
C address for systems that may have other overlapping addresses for other I
2
C
devices.
SDA
SCLK
Si5341/40
I2C_SEL
VDD
VDDI2C
To I
2
C Bus or
Host
A0
A1
LSBs of I
2
C
Address
I
2
C
Figure 8.2. I
2
C Configuration
The 7-bit slave device address of the Si5341/40 consists of a 5-bit fixed address plus two pins that are selectable for the last two bits,
as shown in the following figure.
Slave Address
1 1 1 0 1 A0
0123456
A1
Figure 8.3. 7-bit I
2
C Slave Address Bit-Configuration
Data is transferred MSB first in 8-bit words as specified by the I
2
C specification. A write command consists of a 7-bit device (slave)
address + a write bit, an 8-bit register address, and 8 bits of data as shown in Figure 8.4 I
2
C Write Operation on page 39. A write burst
operation is also shown where subsequent data words are written using to an auto-incremented address.
Si5341, Si5340 Rev D Family Reference Manual • Serial Interface
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
38 Rev. 1.3 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • July 26, 2021 38
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