SI270X-A-EVB Silicon Laboratories Inc, SI270X-A-EVB Datasheet - Page 23

• Manufacturer Part Number: SI270X-A-EVB
• Description: BOARD EVAL FOR SI270X-A
• Manufacturer: Silicon Laboratories Inc

Specifications of SI270X-A-EVB

• Board Type: Fully Populated
• Amplifier Type: Class D
• Output Type: 2-Channel (Stereo) with Stereo Headphones
• Max Output Power X Channels @ Load: 5W x 2 @ 3 Ohm
• Voltage - Supply: 9V
• Utilized Ic / Part: SI270X-A
• Description/function: Audio Amplifiers
• Output Power: 5 W
• Product: Audio Modules
• For Use With/related Products: Si270x
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Operating Temperature: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1929

Si2704/05/06/07-A10
R1
Audio Left
OUTSEL
Audio Right
R2
Figure 16. Headphone Plug Detection Application Schematic
4.4. Clocking
A low jitter on-chip PLL synchronizes to an external clock reference and generates all necessary internal clocks.
2
Three options are available for the external reference: a crystal, a reference clock or the digital I
S audio bit clock.
In addition, a buffered user-programmable output clock can be generated on the CLKO pin for use as a clock
reference for external circuits.
4.4.1. Reference Clock Input
Using an external crystal, the on-chip crystal oscillator generates a precise, low jitter internal clock reference for the
best audio performance.
For system design flexibility, the device also supports the options to use either an external reference clock or the
2
I
S bit clock as the PLL reference. Noise performance of the amplifier is a direct function of the jitter characteristics
of the external source.
The source of the external reference is programmed using the CLOCK_SOURCE property through the 2-Wire
interface.
4.4.1.1. Crystal Oscillator Operation
When a crystal is connected between XTLI and XTLO pins and the chip is configured properly all the timing for the
chip is derived from the on-chip crystal oscillator.
A range of crystals are supported and the device needs to be programmed to the selected frequency using the
CLOCK_REF_FREQ property. The crystal oscillator provides the best audio performance.
4.4.1.2. External Reference Clock Operation
In this mode, the device operates in slave clock mode and the reference clock is provided by an external clock
source on pin XTLI. A wide range of input clock frequencies are supported in this mode ranging from 2.048 to
49 MHz. Refer to Table 11 on page 12 or to the “AN469: Si270x Programming Guide” for more information on the
complete range of frequencies and settings required for operation on this mode.
2
4.4.1.3. I
S Reference Clock Operation
2
The device can operate in slave clock mode using the DCLK signal from the I
S bus as a timing reference. In this
2
mode the device needs to be programmed for one of the supported I
S clock rates and pin XTLI should be
connected to ground.
4.4.2. Reference Clock Output
The Si2704/05/06/07 may provide a buffered output clock to be used as reference for external circuits when the
chip is programmed for either Active or Standby mode. The clock output frequency and synchronization source is
programmable.
The Si270x supports a number of reference clock frequencies that are related to the PWM switching rate. These
CLKO output frequencies can be especially useful for synchronizing the amplifier to switching power supplies.
Refer to the “AN469: Si270x Programming Guide” for more information on the settings requested for operation.
Rev. 0.6
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