User Manual

12311-MRB
12311 Development Hardware Reference Manual, Rev. 1
3-6 Freescale Semiconductor
The 12311-MRB uses a flexible RF path topology that make it suitable for working in different frequency
bands by replacing a minimum number of components while providing good RF performance. The
following table shows the different BOM according to different Frequency Bands of operation.
NOTE
See the MC12311 Data Sheet and Reference Manual for more RF design
information.
Figure 3-4. 12311-MRB RF Circuitry
3.2.2 Clocks
The MC12311 provides for two clocks:
• 32 MHz Reference Oscillator - Figure 3-5 shows the external 32 MHz external crystal Y1. This
mounted crystal must meet the MC12311 specifications.
— Capacitors C22 and C25 provide the bulk of the crystal load capacitance.
— Signal DIO5/CLKOUT can be used to supply an external clock to MCU die and to measure a
the 32MHz oscillator frequency.
— The 12311-MRB has provision for injecting an external 32 MHz clock source as an alternative
to use of the onboard crystal:
– The crystal Y1 should be removed
– C23 must be mounted
– The external 32 MHz source is connected to 2-pin header J4.
• Optional 32.768 kHz Crystal Oscillator - Provision is also made for a secondary 32.768 kHz crystal
Y2 (see Figure 3-6). This oscillator can be used for a low power accurate time base.