NJM2550
10.7MHz INPUT FM IF DEMODULATOR
GENERAL DESCRIPTION
The
NJM2550
is a wide-operating voltage, low-current FM IF
demodulator IC with 10.7MHz(standard) IF frequency.
It includes a limiting amplifier, quadrature detector, filter amplifier,
FSK/ASK(OOK) comparator, RSSI thermal characteristics correction,
and quick charge circuit
The
NJM2550
is suitable for low power, narrow band receiver for
short range data/voice transmission by using IF=10.7MHz or IF/carrier
frequency of up to 50MHz.
PACKAGE OUTLINE
NJM2550V
FEATURES
Wide Range Operating Voltage
Low Operating Current
Wide Range IF Input Frequency
2V to 9V
4.4mA at V
+
=3V
10.7MHz (standard)
5MHz to 50MHz (reference value)
1MHz (reference value)
2Mbps (reference value)
Wide Band FM Detector Circuit
High-speed Transmission Rate
FSK/ASK (OOS) Comparator
Two External Resistors to Adjust RSSI ‘s Thermal Characteristics
Bipolar Technology
Package Outline
SSOP16
BLOCK DIAGRAM
RSSI
OUT
16
CHARGE COMP
SWITCH
OUT
15
14
COMP
REF
13
COMP
IN
12
FSK
VREF
11
AMP
OUT
10
AMP
IN
9
BUFF
AMP
+
-
-
+
-
COMP
CHARGE
RSSI
IF AMP
QUAD DET
1
RSSI
REF
2
GND
3
IF
IN
4
DEC
5
V+
6
IF
OUT
7
QUAD
IN
8
AF
OUT
Ver.2006-02-24
-1-
NJM2550
ABSOLUTE MAXIMUM RATINGS
PARAMETER
Supply Voltage
Power Dissipation
Operating Temperature
Storage Temperature
SYMBOL
V
+
P
D
Topr
Tstg
RATINGS
10.0
300
- 40 to +85
- 40 to +125
(Ta=25°C)
UNIT
V
mW
°C
°C
RECOMMENDED OPERATIONAL CONDITION
PARAMETER
Supply Voltage
SYMBOL
V
+
TEST CONDITIONS
MIN.
2.0
TYP.
3.0
MAX.
9.0
(Ta=25°C)
UNIT
V
ELECTRICAL CHARACTERISTICS
(
Ta=25°C, V
+
=3 V, f i f=10.7MHz, fmod=1kHz, fdev=±100kHz, unless otherwise noted)
PARAMETER
Current Consumption
IF Amplifier Input Resistance
Signal to Noise Ratio 1
SYMBOL
Iccq
Rin
S/N1
VinIF=80dBuV
f i f = 10.7MHz
- 3dB Limiting Sensitivity
Vin(lim)
f i f = 50MHz
Demodulated Signal Level
Demodulated Signal Frequency
Characteristics
Buffer Amplifier Gain
AM Rejection Ratio
Duty Ratio of Wave Shaped Output
Quick Charge / Discharge Current
V od
fDET
Gamp
AMR
DR
I ch
VinIF=80dBuV
Based on fmod=1kHz
Measured at –3dB
1MHz
VinIF=80dBuV
AM=30%
VinIF=80dBuV
V
COMP REF
=GND
V
COMP IN
= 0.3V
-
80
-
-1
-
40
120
-
-
(40)
120
1
0
50
50
210
3
0.1
-
180
-
1
-
60
300
-
-
mVrms
MHz
dB
dB
%
uA
V
V
TEST CONDITIONS
No Signal
V
COMP REF
=0.6V
V
COMP IN
= 0.65V
MIN.
-
-
-
-
TYP.
4.4
330
60
30
MAX.
5.8
-
-
-
UNIT
mA
Ω
dB
dBuV
High Level Voltage of
VfskH
1kΩ load
COMP OUT Terminal
Low Level Voltage of
VfskL
1kΩ load
COMP OUT Terminal
The values shown in parenthesis are reference values.
Ver.2006-02-24
-2-
NJM2550
PARAMETER
RSSI Dynamic Range
Low Level Voltage of RSSI
High Level Voltage of RSSI
RSSI Output Voltage 1
RSSI Output Voltage 2
1pin Terminal Voltage
SYMBOL
∆
RSSI
VrssiL
VrssiH
Vrssi1
Vrssi2
V 1p
No signal
VinIF=110dBuV
VinIF=80dBuV
f i f =50MHz,
VinIF=80dBuV
33kΩ load
TEST CONDITIONS
MIN.
-
-
-
-
-
-
TYP.
65
100
1.55
1.2
1.15
1.1
MAX.
-
-
-
-
-
-
UNIT
dB
mV
V
V
V
V
REFERENCE
(
Ta=25°C, V
+
=3 V, f i f=10.7MHz, fmod=1kHz, fdev=±100kHz, unless otherwise noted)
PARAMETER
SYMBOL
-
RSSI Output Signal Rise-up Time
-
-
FM Demodulated Signal Rise-up Time
-
TEST CONDITIONS
V
+
=on
IF Signal = off on
IF Signal=on
V
+
= off on
V
+
=on
IF Signal = off on
IF Signal=on
V
+
= off on
MIN.
-
-
-
-
TYP.
50
600
20
600
MAX.
-
-
-
-
UNIT
usec
usec
usec
usec
Ver.2006-02-24
-3-
NJM2550
TEST CIRCUIT
This test circuit allows the measurement of all parameters described in “ELECTRICAL CHARACTERISTICS”. This
test circuit includes an electrical switch that should be in the suitable position for the measurement of each
parameter.
Circuit Diagram
RSSI
OUT
CHARGE
SWITCH
V
+
100k
COMP
OUT
100k
10u
+
AMP
OUT
3300p
100k
330p
11
10
9
BUFF
AMP
68k
68k
68k
1000p
1000p
7.5k
16
15
14
13
12
+
+
--
+
-
COMP
CHARGE
RSSI
IF AMP
QUAD DET
1
2
3
0.01u
4
0.01u
5
6
2p
V
+
+
7
R50
8
R10
1k
V
+
AF
OUT
33k
30p
RSSI
REF
51
IF
IN
10u 0.1u
Tquad
External Components
•
f i f =10.7 MHz
Tquad : IF transformer for detection, 4165-T070 (Sumida corporation)
R10
: 1kΩ
R50
: open
•
f i f =50MHz
Tquad : IF transformer for detection, 2261-T080 (Sumida corporation)
R10
: 1kΩ
R50
: 7.5 kΩ
•
The external resistors connected to1pin and 16pin should have the same thermal coefficient.
Ver.2006-02-24
-4-
NJM2550
TERMINAL FUNCTION (
Ta=25°C, V
+
=3 V
)
Pin No.
SYMBOL
EQUIVARENT CIRCUIT
V+
VOLTAGE
FUNCTION
RSSI Reference Current
Control
To control RSSI reference current,
a resistor is connected to pin1 and
pin6, respectively.
The recommended value is 33kΩ.
By choosing the different thermal
coefficient of these two resisters,
RSSI thermal characteristics can
be changed.
1
RSSI REF
1
50k
1.12V
GND
2
GND
--
V+
--
Ground
IF Limiter Amplifier Input
The typical input impedance is
330Ω.
3
IF IN
165
64k
2.46
165
3
4
DEC
4
GND
IF Decoupling
An external decoupling capacitor
is connected to enhance stability.
2.46V
Supply Voltage
5
V+
5
V
+
GND
--
V+
IF Limiter Amplifier Output
An external phase-shifting coil or
discriminator is connected
between pin6 and pin7.
2.06V
6
IF OUT
6
140uA
GND
Ver.2006-02-24
-5-
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