MICRF219 datasheet(14/23 Pages) MICREL

14 / 23 page

Micrel

MICRF219

M9999-060811

(408) 944-0800

Crystal Selection

June 2011

Figure 6. Plotting of Shunt Inductor and Series

Capacitor

ed respectively) is the

internal circuits.

F load capacitance,

+105ºC temperature

crel’s approved

(www.hib.com.br

Crystal Y1 or Y1A (SMT or lead

reference clock for all the device

Crystal characteristics of 10p

30ppm, ESR < 50Ω,

−40ºC to

range are desired. Table 4 shows Mi

crystal

suppliers

such

http://www.abracon.com/ ) and

The oscillator of the MICRF219 i

oscillator. Good care must be

the printed circuit board. Avoi

the ground plane on the to

REFOSC pins RO1 and RO2. Wh

in the layout, and the crystals

the frequencies.

s a Pierce-type

taken when laying out

d long traces and place

p layer close to the

en care is not taken

used are not verified,

the oscillator may take longer time to start. Time-to-

be longer as well. In

citance is too high (>

the receiving central

r the oscillator may not

C = RF

cal oscillator is low-side

injection (32 × 13.52127MHz = 432.68MHz), that is,

its frequency is below the RF carrier frequency and

the image frequency is below the LO frequency. See

Figure 7. The product of the incoming RF signal and

good-data in the DO pin will

some cases, if the stray capa

20pF). In this case, either

frequency will offset too much o

start.

The crystal frequency is calculated by REFOS

Carrier/(32+(1.1/12)). The lo

local oscillator signal will yield the IF frequency, which

will be demodulated by the detector of the device.

Figure 7. Low-Side Injection Local Oscillator

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