4.8.1.1 Use Without PLL
4.8.1.2 Use With The PLL
4.8.1.3 Setting the ADC and DAC Sampling Rates
TLV320AIC3104EVM Software
Setting up the TLV320AIC3104 for clocking without using the PLL permits the lowest power consumption
by the codec. The CLKDIV_IN source can be selected as either MCLK, GPIO2, or BCLK, the default is
MCLK. The CLKDIV_IN frequency is then entered into the CLKDIV_IN box, in megahertz (MHz). The
default value shown, 11.2896 MHz, is the frequency used on the USB-MODEVM board. This value is then
divided by the value of Q, which can be set from 2 to 17; the resulting CLKDIV_OUT frequency is shown
in the indicator next to the Q control. The result frequency is shown as the Actual Fsref.
When PLLDIV_OUT is selected as the codec clock source, the PLL will be used. The PLL clock source is
chosen using the PLLCLK_IN control, and may be set to either MCLK, GPIO2, or BCLK. The PLLCLK_IN
frequency is then entered into the PLLCLK_IN Source box.
The PLL_OUT and PLLDIV_OUT indicators show the resulting PLL output frequencies with the values set
for the P, K, and R parameters of the PLL. See the TLV320AIC3104 data sheet for an explanation of
these parameters. The parameters can be set by clicking on the up/down arrows of the P, K, and R
combo boxes, or they can be typed into these boxes.
The values can also be calculated by the PC software. To use the PC software to find the ideal values of
P, K, and R for a given PLL input frequency and desired Fsref:
1. Verify the correct reference frequency is entered into the PLLCLK_IN Source box in megahertz (MHz)
2. The desired Fsref should be set using the Fsref switch.
3. Push the Search for Ideal Settings button. The software will start searching for ideal combinations of
P, K, and R which achieve the desired Fsref. The possible settings for these parameters are displayed
in the spreadsheet-like table labeled Possible Settings.
4. Click on a row in this table to select the P, K, and R values located in that row. Notice that when this is
done, the software updates the P, K, R, PLL_OUT, and PLLDIV_OUT readings, as well as the Actual
Fsref and Error displays. The values show the calculations based on the values that were selected.
This process does not actually load the values into the TLV320AIC3104, however; it only updates the
displays in the software. If more than one row exists, the user can choose the other rows to see which
of the possible settings comes closest to the ideal settings.
When a suitable combination of P, K, and R have been chosen, pressing the Load Settings into Device?
button will download these values into the appropriate registers on the TLV320AIC3104.
The Fsref frequency that is determine either enabling or bypassing the PLL (see Section 4.8.1.1 or
Section 4.8.1.2 ) is used to determine the actual ADC and DAC sampling rates. Using the NADC and
NDAC factors the sampling rates are derived from the Fsref. If dual rate mode is desired, this option can
be enabled for either the ADC or DAC by pressing the corresponding Dual Rate Mode button. The ADC
and DAC sampling rates are shown in the box to the right of each control.
TLV320AIC3104EVM and TLV320AIC3104EVM-PDK18 SLAU218 – August 2007
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