RFPIC12F675H Microchip Technology Inc., RFPIC12F675H Datasheet - Page 56

• Manufacturer Part Number: RFPIC12F675H
• Description: 20-pin Flash-based 8-bit Cmos Microcontroller With Uhf Ask/fsk Transmitter
• Manufacturer: Microchip Technology Inc.

rfPIC12F675
9.9
The mode control logic pin RFEN controls the
the crystal oscillator starts up. The voltage on the LF
pin ramps up proportionally to the RF frequency. The
PLL can lock onto the frequency faster than the start-
ing up crystal can stabilize. When the LF pin reaches
0.8V, the RF frequency is close to locked on the crys-
tal frequency. This initiates a 150 microsecond delay
to ensure that the PLL settles. After the delay, the PS
bias current and power amplifier are enabled to start
transmitting when DATA
When RFEN is low, the transmitter goes into a very
low power Standby mode. The power amplifier is
pin has an internal pull-down resistor.
9.10
The rfPIC12F675 transmitter has a built in low voltage
disable centered at about 1.85V. If the supply voltage
drops below this voltage the power amplifier is
DS70091A-page 54
operation of the transmitter. When RFEN goes high,
disabled and the crystal oscillator stops. The RFEN
disabled to prevent uncontrolled transmissions.
Digital Control Signals
Low Voltage Output Disable
ASK
goes high.
Preliminary
 2003 Microchip Technology Inc.