I2C Interface; Slave Address - Silicon Laboratories SI5351A/B/C Product Manual

Si5351A/B/C
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4. I C Interface
Many of the functions and features of the Si5351 are controlled by reading and writing to the RAM space using the
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I C interface. The following is a list of the common features that are controllable through the I
summary of register functions is shown in Section 7.
 Read Status Indicators
Loss of signal (LOS) for the CLKIN input

Loss of lock (LOL) for PLLA and PLLB

 Configuration of multiplication and divider values for the PLLs, MultiSynth dividers
 Configuration of the Spread Spectrum profile (down or center spread, modulation percentage)
 Control of the cross point switch selection for each of the PLLs and MultiSynth dividers
 Set output clock options
Enable/disable for each clock output

Invert/non-invert for each clock output

Output divider values (2

Output state when disabled (stop hi, stop low, Hi-Z)

Output phase offset

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The I C 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.
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The I C bus consists of a bidirectional serial data line (SDA) and a serial clock input (SCL) as shown in Figure 7.
Both the SDA and SCL pins must be connected to the VDD supply via an external pull-up as recommended by the
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I C specification.
The 7-bit device (slave) address of the Si5351 consist of a 6-bit fixed address plus a user selectable LSB bit as
shown in Figure 8. The LSB bit is selectable as 0 or 1 using the optional A0 pin which is useful for applications that
require more than one Si5351 on a single I
Data is transferred MSB first in 8-bit words as specified by the I
bit device (slave) address + a write bit, an 8-bit register address, and 8 bits of data as shown in Figure 9. A write
burst operation is also shown where every additional data word is written using to an auto-incremented address.
14
n
, n=1.. 7)
VDD
>1k
>1k
SCL
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I C Bus
SDA
4.7 k
INTR
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I C Address Select:
A0
Pull-up to VDD (A0 = 1)
Pull-down to GND (A0 = 0)
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Figure 7. I C and Control Signals
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C bus.
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Slave Address

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Figure 8. Si5351 I
Preliminary Rev. 0.95
Si5351
5 4 3 2 1 0
1 0 0 0 0 0/1
A0
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C Slave Address
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C specification. A write command consists of a 7-
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C interface. A