micrf220 Micrel Semiconductor, micrf220 Datasheet - Page 11

• Manufacturer Part Number: micrf220
• Description: 300mhz To 450mhz, 3.3v Ask/ook Receiver With Rssi And Squelch
• Manufacturer: Micrel Semiconductor

Micrel, Inc.
Reference oscillator crystal frequency can be calculated
according to Equation 3. For example, if f
f
frequencies at different popular RF frequencies.
operate the MICRF220 with minimum offset, use proper
loading
manufacturer.
*Empirically derived, slightly different from Equation 3.
Squelch Operation
When squelch function is enabled by tying the SQ pin low,
the chip will monitor incoming pulse width before allowing
activity on DO pin. The pulse width is set by SEL1 and
SEL0 pins as shown in Table 5, and is inversely
proportional to frequency. When there is no input signal
and squelch is not enabled (SQ pin left floating), voltage on
DO chatters due to random noise as shown in Figure 6. If
SQ pin is tied low, the activity on DO pin is much reduced
as shown in Figure 7.
August 2010
REF
RF Input Frequency (MHz)
RO2
RO1
= 13.52313MHz. Table 4 lists the values of reference
capacitance
Table 4. Reference Frequency Examples
Figure 5. Reference Oscillator Circuit
433.92
315.0
390.0
418.0
C
C
recommended
R
Reference Frequency (MHz)
V BIAS
13.52313*
12.15446
13.02708
9.81713*
by
RF
= 433.92MHz,
the
crystal
To
11
When squelch function is enabled by tying the SQ pin low,
the chip will monitor incoming pulse width before allowing
activity on DO pin. The pulse width is set by SEL1 and
SEL0 pins as shown in Table 5, and is inversely
proportional to frequency. When there is no input signal
and squelch is not enabled (SQ pin left floating), voltage on
DO chatters due to random noise as shown in Figure 6. If
SQ pin is tied low, the activity on DO pin is much reduced
as shown in Figure 7.
Figure 6. Data Out Pin with No Squelch (V
Figure 7. Data Out Pin with Squelch (V
M9999-082610-A
SQ
SQ
= 0V)
MICRF220
= V
DD
)