CC2541 external crystals

Hello Xueting, 

For operation of transceiver on CC2541, high precision clock reference is required. 32MHz crystal oscillator (and hence 32MHz crystal) provides this clock. 32KHz oscillator is used in power modes to keep the current consumption low when not in active mode. Even though it is possible to use 32KHz RC oscillator in these modes, to meet precise timing requirements, 32KHz crystal oscillator (and hence an external 32KHz crystal) is required.

For further details, please refer to section 4.4 in the following user guide. 

http://www.ti.com/lit/ug/swru191f/swru191f.pdf

Regards,
SVS

Just to clarify the precision timing of the 32kHz crystal is required for designs that will be BLE certified and are using low power modes, otherwise the option is available to use the 32kHz RC oscillator.

See previous post for more details.

http://e2e.ti.com/support/low_power_rf/f/538/t/258847.aspx

Regards,

BK

Hi,

You are correct, external crystal spec is defined by internal HW architecture of cc2541 device