MRF39RA Datasheet, PDF (19/72 Pages) Microchip Technology – Low-Power, Integrated UHF Receiver

2.4.18 TEMPERATURE SENSOR
When temperature is measured, the receiver ADC is
used to digitize the sensor response. Most receiver
blocks are disabled, and temperature measurement
can only be triggered in Standby or Frequency
Synthesizer modes.
As shown in Figure 2-11, the response of the
temperature sensor is -1°C/Lsb. A CMOS temperature
sensor is not accurate by nature; therefore, it must be
calibrated at ambient temperature for precise
temperature readings.
FIGURE 2-11:
TEMPERATURE SENSOR RESPONSE
TempValue
TempValue(t)
TempValue(t)-1
Returns 150d (typ.)
Needs calibration
-1°C/Lsb
MRF39RA
-40°C
t t+1
Ambient
It takes less than 100 microseconds for the MRF39RA
to evaluate the temperature from setting
TempMeasStart to ‘1’ to TempMeasRunning Reset.
2.4.19 TIME-OUT FUNCTION
The MRF39RA includes a time-out function, which
enables it to automatically shut down the receiver after
a receive sequence and, therefore, save energy.
• Time-out interrupt is generated,
TimeoutRxStart x 16 x Tbit, after switching to RX
mode if RssiThreshold flag does not raise within
this time frame.
• Time-out interrupt is generated,
TimeoutRssiThresh x 16 x Tbit, after
RssiThreshold flag is raised.
Use Time-out interrupt to warn the companion
processor to shut down the receiver and return to a
lower power mode.
+85°C
 2015 Microchip Technology Inc.
DS40001778B-page 19