Document Number: 002-14806 Rev. *C

Page 23 of 52

PRELIMINARY

CYW20713

Package Options and TCXO Mode

Only a few package options bring out TM0 to balls, allowing the application to configure them. In most packages, these pins are already

configured.

Table 6 lists available package options.

6.4 Frequency Selection

Any frequency within the range specified for the crystal and TCXO reference can be used. These frequencies include standard handset

reference frequencies (12, 13, 14.4, 15.36, 16.2, 16.8, 18, 19.2, 19.44, 19.68, 19.8, 20, 24, 26, 33.6, 37.4, and 38.4 MHz) and any

frequency between these reference frequencies, as desired by the system designer. Since bit timing is derived from the reference

frequency, the CYW20713 must have the reference frequency set correctly in order for the UART and PCM interfaces to function

properly.

The CYW20713 reference frequency can be set in one of three ways.

The CYW20713 is set to a default frequency of 20 MHz at the factory. For a typical design using a crystal, it is recommended that the

default frequency be used, since this simplifies the design by removing the need for either external NVRAM or external LPO clock.

If the application requires a frequency other than the default, the value can be stored in an external NVRAM. Programming the

reference frequency in NVRAM provides the maximum flexibility in the selection of the reference frequency, since any frequency within

the specified range for crystal and external frequency reference can be used. During power-on reset (POR), the device downloads

the parameter settings stored in NVRAM, which can be programmed to include the reference frequency and frequency trim values.

Typically, this is how a PC Bluetooth application is configured.

For applications such as handsets and portable smart communication devices, where the reference frequency is one of the standard

frequencies commonly used, the CYW20713 automatically detects the reference frequency and programs itself to the correct

reference frequency. In order for auto-frequency detection to work properly, the CYW20713 must have a valid and stable 32.768 kHz

external LPO clock present during POR. This eliminates the need for NVRAM in applications where the external LPO clock is available

and an external NVRAM is typically not used.

6.5 Frequency Trimming

The CYW20713 uses a fractional-N synthesizer to digitally fine-tune the frequency reference input to within ±2 ppm tuning accuracy.

This trimming function can be applied to either the crystal or an external frequency source such as a TCXO. Unlike the typical crystal-

trimming methods used, the CYW20713 changes the frequency using a fully digital implementation and is much more stable and

unaffected by crystal characteristics or temperature. Input impedance and loading characteristics remain unchanged on the TCXO or

crystal during the trimming process and are unaffected by process and temperature variations.

The option to use or not use frequency trimming is based on the system designer’s cost trade-off between bill-of-materials (BOM) cost

of the crystal and the added manufacturing cost associated with frequency trimming. The frequency trimming value can either be

stored in the host and written to the CYW20713 as a vendor-specific HCI command or stored in NVRAM and subsequently recalled

during POR.

Frequency trimming is not a substitute for the poor use of tuning capacitors at an crystal oscillator (XTAL). Occasionally, trimming can

help alleviate hardware changes.

Table 6. Package Options

Part Number

Package Description

TM0

CYW20713A1KUFBXG

50-ball FPBGA

Brought to ball

CYW20713A1KUBG

42-bump WLBGA

1