TRC105 RFM, TRC105 Datasheet - Page 51

• Manufacturer Part Number: TRC105
• Description: IC TXRX 300MHZ-510MHZ 32TQFN
• Manufacturer: RFM

Specifications of TRC105

• Frequency: 300MHz ~ 510MHz
• Data Rate - Maximum: 200kbps
• Modulation Or Protocol: FSK, OOK
• Applications: General Purpose
• Power - Output: 13dBm
• Sensitivity: -112dBm
• Voltage - Supply: 2.1 V ~ 3.6 V
• Current - Receiving: 3mA
• Current - Transmitting: 30mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-TQFN
• Wireless Frequency: 300 MHz to 510 MHz
• Output Power: 13 dBm
• Operating Supply Voltage: 2.1 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Maximum Supply Current: 1.7 mA
• Minimum Operating Temperature: - 40 C
• Modulation: FSK, OOK
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 583-1159-2

6.3.2 OOK Demodulator Related Configuration Values
OOK demodulation in the TRC105 is accomplished by comparing the RSSI to a threshold value. An RSSI value
greater than the threshold is “sliced” to a logic 1, and an RSSI value equal or less than the RSSI value is sliced to
a logic 0. The TRC105 provides three threshold options - fixed threshold, average-referenced threshold, and
peak-referenced threshold. MCFG01 bits 3..2 select the OOK threshold as shown in Table 62:
The configuration settings for each of these threshold options depends directly or indirectly on the bit rate.
The fixed-threshold value is configured in MCFG13. The fixed threshold can be adjusted in 0.5 dB increments
over a range of 128 dB. Also, the gain of the IF can be adjusted over a range of 13.5 dB to reduce the RSSI value
under no signal conditions. MCFG01 bits 1..0 select the IF gain as shown in Table 63:
The useable threshold setting depends on the RF operating band, the bandwidths of the receiver filters, the RF
noise generated by host circuitry, the RF noise generated in the application environment, and the antenna effi-
ciency. The fixed threshold is adjusted heuristically by incrementing the threshold while monitoring the data output
pin with an oscilloscope. The threshold is adjusted upward under no signal conditions until noise spikes on the
data output are reduced to an average of one spike every five or more seconds. Because the fixed threshold has
no automatic adjustment capability, it should only be used in applications where incidental RF noise generators
such as PCs, switchgear, etc., are not present.
The average-referenced threshold is generated by passing the RSSI signal through a low-pass filter. Four cutoff
frequencies can be configured for this filter with RXCFG15 bits 1..0, as shown in Table 64 below:
The chip rate is equal to the bit rate except when Manchester encoding is used. For Manchester encoding, the
chip rate is equal to twice the bit rate. An adequately long 1-0-1-0… preamble must be transmitted to center the
average-referenced threshold. A preamble of at least 24 bits is recommended. The average-referenced threshold
should be used in conjunction with a mechanism to avoid transmitting a long sequence of bits of the same value,
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Pattern of Bits 3..2
Pattern of Bits 1..0
Pattern of Bits 1..0
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Table 62
Table 63
Table 64
average referenced
Cutoff Frequency
peak referenced
chip rate/32*π
chip rate/8*π
chip rate/4*π
chip rate/2*π
Threshold
maximum
not used
-13.5 dB
IF Gain
-4.5 dB
-9.0 dB
fixed
TRC105 - 11/01/10
Page 51 of 66