CS43131 datasheet(63/156 Pages) CIRRUS

63 / 156 page

DS1155F1

CS43131

5 Applications

This section provides recommended application procedures and instruction sequences for standard CS43131 operations.

5.1 PLL Clocking

Data-path logic is in the MCLK_INT domain, where MCLK_INT is expected to be 22.5792 or 24.576 MHz. For clocking

scenarios in which the external system MCLK provided to CS43131 is neither 22.5792 nor 24.576 MHz, the PLL must be

turned on to provide the desired internal MCLK. At start up, the system uses RCO as the internal MCLK for PLL

programming over I2C and switches to the PLL output after it settles. PLL start-up time is a maximum of 1 ms.

5.2 Power Sequencing

Note the following for power-up sequencing on the CS43131:

• VP must be powered up first.

• All other supplies can come up in any order before RESET is released.

Note the following for power-down sequencing on the CS43131:

• After RESET is asserted, VA/VCP/VL/VD can be removed in any order.

• VP must be powered down last.

5.3 Crystal Tuning

The CS43131 uses an external crystal as the source for internal MCLK. Refer to Table 3-16 for the load capacitance that

is supported by CS43131. Table 5-1 lists supported crystals that meet the requirements for CS43131 and also shows also

shows the XTAL_IBIAS settings for different crystals.

The crystal setting register (0x20052) must be set appropriately based on the crystal used.

The frequency at which the crystal eventually oscillates can be calculated using the formula below:

Fosc= 1/(2*π*sqrt[Lm*(Cm (C0+CL))/(Cm+C0+CL)]) ,

where

Lm = motional inductance of crystal

Cm = motional capacitance of crystal

C0 = shunt capacitance

CL = load capacitance

Trace capacitance and pad capacitance (approximately 0.5 pF) must also be taken into account while calculating the value

of the load capacitors. Below are the steps to tune the crystal to the correct frequency:

1. Select load capacitor values that match the load capacitance spec in crystal manufacturer's data sheet.

Table 5-1. Example List of Supported Crystals

Manufacturer 1

1.Contact your local Cirrus Logic representative for a list of supported manufacturers and part numbers.

Part Number 1

Frequency (MHz)

Bias Current

Strength (µA)

Crystal Setting Register

(0x20052)

River Electronics

FCX-06-22.5792J51933

22.5792

12.5

0x04

FCX-06-24.5760J51930

24.576

7.5

0x06

NDK

NX2016SA 22.5792M EXS00A-CS09116

22.5792

0x02

NX2016SA 24.576M EXS00A-CS09117

24.576

TXC

8Y22570001

22.5792

12.5

0x04

8Y24570001

24.576

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