MICRF112 データシートの表示（PDF） - Micrel
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MICRF112 Datasheet PDF : 20 Pages
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Micrel, Inc.
Functional Diagram
MICRF112
Figure 3. Functional Block Diagram MICRF112 10 Pin ASK / FSK Version
Functional Description
Figure 3 shows a functional block diagram of the
MICRF112 transmitter. The MICRF112 can be best
described as a phase locked transmitter. The system
can be partitioned into six functional blocks; crystal
oscillator, PLL×32, power amplifier, enable control,
under voltage detect and open drain switch for FSK
operation.
Crystal Oscillator
The reference oscillator is crystal-based Pierce
configuration. It is designed to accept crystals with
frequency from 9.375MHz to 14.0625MHz.
Crystal Oscillator Parameters for ASK Operation
Figure 4 shows a reference oscillator circuit
configuration for ASK operation. The reference oscillator
is capable of driving crystals with ESR range from 20Ω
to 300Ω.
When the ESR of crystal is at 20Ω, the crystal parameter
limits are:
ESR 20Ω
CPAR 2 to 10pF
CMO 10 to 40fF
Figure 4. Reference Oscillator ASK Operation
When the ESR of crystal is at 300Ω, the crystal
parameter limits are:
ESR
300Ω
CPAR
CMO
CLOAD
2 to 5pF
10 to 40fF
10 to 30pF
December 2011
12
M9999-120911
(408) 944-0800
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