NJM2211M NJR, NJM2211M Datasheet - Page 8

• Manufacturer Part Number: NJM2211M
• Description: IC FSK DEMOD/ TONE DECODER S014
• Manufacturer: NJR

Specifications of NJM2211M

• Function: Demodulator
• Current - Supply: 11mA
• Voltage - Supply: 4.5 V ~ 20 V
• Package / Case: 14-DMP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Gain: -
• Noise Figure: -
• P1db: -
• Lo Frequency: -
• Rf Frequency: -

Design Example
Step 1 : Calculate f
Step 2 : Choose R0=20kΩ (18kΩ fixed resistor in series with 5kΩ potentiometer)
Step 3 : Calculate C0 from VCO Frequency vs. Timing Capacitor : C0 =0.044µF
Step 4 : Calculate R1 : R1=R0 (1140 / 60) =380kΩ
Step 5 : Calculate C1 : C1=C0 / 4=0.011µF
Note : All values except R0 can be rounded off to nearest standard value.
FSK Decoding With Carrier Detect
circuit connection for this application is shown in Figure 3. The open-collector lock-detect output, pin 6, is shorted to the
data output (pin 7). Thus, the data output will be disabled at "low" state, until there is a carrier within the detection band of
the PLL, and the pin 6 output goes "high" to enable the data output.
the range of incoming frequencies over which the loop can acquire lock and is always less than the tracking range. It is
further limited by C1. For most applications, ∆f
determined by :
frequency approaches the capture bandwidth. Excessively large values of C
lock-detect output.
Tone Detection
normally at "high" and "low" logic states, respectively. When a tone is present within the detection band of the PLL, the
logic state at these outputs becomes reversed for the duration of the input tone. Each logic output can sink 5mA of load
current.
shown in Figure 4.
C0 set VCO center frequency, R1 sets the detection bandwidth, C1 sets the lowpass-loop filter time constant and the
loop damping factor, and R
Figure 3. FSK Demodulation with Carrier Detect Capability
- 8 -
With reference to Figure 1 and 4, the function of the external circuit components can be explained as follows : R0 and
75 Band FSK demodulator with mark / space frequencies of 1110 / 1170Hz :
The lock-detect section of the NJM2211 can be used as a carrier detect option for FSK decoding. The recommended
The Minimum value of the lock-detect filter capacitance C
C
With values of C
Figure 4 shows the generalized circuit connection for tone detection. The logic outputs, Q and Q at pins 5 and 6 are
Both logic outputs at pins 5 and 6 are open-collector type stages, and require external pull-up resistors R
D
(µF) ≥ 16 / capture range in Hz
f
0
=(1110+1170) (1 / 2)=1140Hz
0
:
D
that are too small, chatter can be observed on the lock-detect output as an incoming signal
L1
and R
L2
are the respective pull-up resistors for the Q and Q logic outputs.
c
<∆f / 2, For R
D
is inversely proportional to the capture range, ±∆f
D
=470kΩ, the approximate minimum value of C
Figure 4. Tone Detection
D
will slow the response time of the
L1
Ver.2003-12-09
and R
D
c
. This is
can be
L2
as