mc68hc908rf2 Freescale Semiconductor, Inc, mc68hc908rf2 Datasheet - Page 149

• Manufacturer Part Number: mc68hc908rf2
• Description: M68hc08 Microcontrollers Microcontroller / Transmitter
• Manufacturer: Freescale Semiconductor, Inc

12.2 Transmitter Functional Description
12.3 Phase-Lock Loop (PLL) and Local Oscillator
12.4 RF Output Stage
MC68HC908RF2 — Rev. 4.0
MOTOROLA
The transmitter is a phase-locked loop (PLL) tuned low-power UHF transmitter.
The different modes of operation are controlled by the microcontroller through
several digital input pins. The power supply voltage ranges from 1.9 V to 3.7 V
allowing operation with a single lithium cell.
The VCO is a completely integrated relaxation oscillator. The phase frequency
detector (PFD) and the loop filter are fully integrated. The exact output frequency
is equal to:
The frequency band of operation is selected through the BAND pin.
provides details for each frequency band selection.
An out-of-lock function is performed by monitoring the internal PFD output voltage.
When it exceeds its limits, the RF output stage is disabled.
The output stage is a single-ended square wave switched current source.
Harmonics will be present in the output current drive. Their radiated absolute level
depends on the antenna characteristics and output power. Typical application
demonstrates compliance to European Telecommunications Standards Institute
(ETSI) standard. A resistor R
power allowing a tradeoff between radiated power and current consumption. The
output voltage is internally clamped to:
V
CC
Freescale Semiconductor, Inc.
± 2 V
For More Information On This Product,
BAND Input
Level
High
BE
Low
PLL Tuned UHF Transmitter Module
(typically V
Go to: www.freescale.com
Table 12-1. Frequency Band Selection
f
and Associated Divider Ratios
RFOUT
Band (MHz)
Frequency
CC
315
434
868
EXT
±1.5 V @ T
= f
connected to the REXT pin controls the output
XTAL
x PLL divider ratio
PLL Divider
A
Ratio
= 25°C)
32
64
PLL Tuned UHF Transmitter Module
Transmitter Functional Description
Crystal Oscillator
Frequency (MHz)
13.56
9.84
Table 12-1
Data Sheet
149