SI4312-B10-GM Silicon Laboratories Inc, SI4312-B10-GM Datasheet - Page 10

• Manufacturer Part Number: SI4312-B10-GM
• Description: IC RX OOK 315/434MHZ 20VQFN
• Manufacturer: Silicon Laboratories Inc
• Series: EZRadio®r
• Type: ISM Receiverr

Specifications of SI4312-B10-GM

• Package / Case: 20-VQFN
• Frequency: 315MHz, 434MHz
• Sensitivity: -110dBm
• Data Rate - Maximum: 10 kBaud
• Modulation Or Protocol: OOK
• Applications: Garage Openers, RKE, Security Alarms
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Operating Frequency: 315 MHz to 434 MHz
• Operating Supply Voltage: 2.7 V to 3.6 V
• Maximum Operating Temperature: + 95 C
• Minimum Operating Temperature: - 45 C
• Mounting Style: SMD/SMT
• Supply Current: 20 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Memory Size: -
• Current - Receiving: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1977-5

Si4312
3.5. RATIO Selection Used for the Slicer Threshold Calculation Window
In OOK modulation, many different encoding schemes exist, which can result in variable ON and OFF times as
seen in the example data waveforms shown in Figure 4. In order to determine the proper slicer threshold used for
demodulating the OOK signal into digital data, the Si4312 must sample an "ON" and "OFF" event in a time window
called the threshold calculation window. The samples during the "ON" time will determine the ON voltage, and the
samples during the "OFF" time will determine the OFF voltage. These voltages are used to determine the slicer
threshold voltage as follows:
Defining the BT variable from the last section as the ON time and
then, the threshold calculation window is calculated as follows:
The threshold calculation window is 1.25 times longer than the ON plus OFF times for margin to allow sampling of
both ON and OFF times. Figure 5 shows a graph of the threshold calculation window.
Ratio is a unit-less multiplier that relates the OFF time to the ON time. The Si4312 defines two constants for RATIO
as shown in Table 10 based on the logic level of pin 5.
10
Digital Data
Waveform
Encoding
OOK
PPM
Table 10. RATIO Constants Based on Logic Level of Pin 5
1000 us
SlicerThreshold
Figure 5. Example of the Threshold Calculation
“1”
Threshold Calculation Window
Pin 5
=
=
0
1
1.25
=
1.25 BT RATIO

---------------------------------------------------------------------------------------------------------- -
Max_ON_Voltage

RATIO

Threshold Calculation Window

BT
Rev. 0.5
ON voltage
“0”
+

BT RATIO
=
OFF
----------- -

ON
=
1.25
+
RATIO
1
+
2


Min_OFF_Voltage
10
5


ON
+
OFF
OFF voltage
100 us
“1”


“1”