NJM2590/97
-1-
V
er.2004-08-25
455kHz INPUT FM IF DEMODULATOR
GENERAL DESCRIPTION P A CKAGE OUTLINE
The NJM2590 and NJM2597 are low current FM IF demodulator
ICs with 455kHz IF input, which operate from 1.6V supply.
The NJM2590/97 contain the minimum functions required to
FM IF demodulator, that is, IF amplifier, quadrature detector,
LPF amplifier, FSK comparator, RSSI, and RSSI comparator.
It offers unmatched design flexibility.
FEATURES
Low Operating Voltage 1.6V to 5.5V
Low Operating Current 550uA at V+ =1.8V
IF Input Frequency 455kHz (standard)
RSSI Comparator
The Range of Linear Area on RSSI Output versus IF Input Characteristics
NJN2590 IF Input level=25 to 60 dBuVEMF (reference value)
NJM2597 IF Input level=35 to 85 dBuVEMF (reference value)
Bipolar Technology
Package Outline SSOP14
BLOCK DIAGRAM
NJM2590V/97V
V
+
IF IN
14 13 12 11 10 9 8
1 2 43 5 6 7
QUAD DET
RSSI
FSK
OUT CHARGE
GND DEC FSK
REF QUAD
IN AF
OUT LPF
IN
LPF
OUT
LPF
RSSI
OUT
RSSI
COMP
SENSE
LEVEL
CARRIER
SENSE
CHARGE
IF AMP
FSK
COMP
NJM2590/97
Ver.2004-08-25
- 2 -
ABSOLUTE MAXIMUM RATINGS (Ta=25°C)
PARAMETER SYMBOL RATINGS UNIT
Supply Voltage V+ 8.0 V
Power Dissipation P D 300 mW
Operating Temperature T o p r - 40 to +85 °C
Storage Temperature T s t g - 40 to +125 °C
RECOMMENDED OPERATIONAL CONDITION (Ta=25°C)
PARAMETER SYMBOL TEST CONDITIONS MIN. TYP. MAX. UNIT
Supply Voltage V+ 1.6 1.8 5.5 V
ELECTRICAL CHA RACTERISTICS (Ta=25°C, V+=1.8V, fin=455kHz, fmod=600Hz, fdev=±4kHz)
PARAMETER SYMBOL TEST CONDITIONS MIN. TYP. MAX. UNIT
Current Consumption I c c q No Signal 440 550 660 uA
IF Amplifier Input Resistance R i n (1.6) 2 (2.4) kΩ
Signal to Noise Ratio 1 S / N 1 Vi=60dBu EMF - 60 - dB
Signal to Noise Ratio 2 S / N 2 Vi=25dBu EMF - 30 - dB
- 3dB Limiting Sensitivity V i n ( l i m ) - 22 27 dBu EMF
Demodulated Output Level V o d Vi=60dBu EMF 35 40 65 mVrms
AM Rejection Raito A M R Vi=60dBu EMF
AM=30% - 50 - dB
Duty Ratio of Wave Shaped Output D R Vi=60dBu EMF 40 50 60 %
Quick Charge/Discharge Current I c h V FSK OUT=GND
V LPF OUT = 0.18V 35 65 110 uA
NJM2590 Vi=40dBu EMF 0.7 0.9 1.1
RSSI Output Voltage
NJM2597
V r s s i
Vi=80dBu EMF 0.8 1.1 1.4
V
High Level Leak Current of
FSK OUT Terminal I f s k H V FSK OUT=V+ (-0.1) (0) (0.1) uA
Low Level Voltage of
FSK OUT Terminal V f s k L I FSK OUT =100uA - 0.1 0.4 V
High Level Leak Current of
CARRIER SENSE Terminal I c r y H V CARRIAR SENSE =V+ (-0.1) (0) (0.1) uA
Low Level Voltage of
CARRIER SENSE Terminal V c r y L I CARRIER SENSE=100uA 0.0 0.1 0.4 V
Bias Current of
SENSE LEVEL Terminal I l e v e l V CARRIER SENSE =0.8V (-1.0) (0) (1.0) uA
The value shown in parenthesis are reference values.
NJM2590/97
V
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3
-
TEST CIRCUIT
This test circuit allows the measurement of all parameters described in “ELECTRICAL CHARACTERISTICS”. This
test circuit includes some electrical switches that should be in the suitable positions for the measurement of each
parameter. For the best measurement of each parameter, the drawings of ”Test Circuit 1 to 10” are additionally
prepared to show the switching positions and other changes of connection. Note that “Test Circuit 1 to 10” are not
the complete circuit to measure.
Note :
1. “CD” means a ceramic discriminator of 455kHz ;
CDBCB455KCAY66-R0(MURATA,JAPAN)
A
123 4 567
A
8
91011
1213
14
RSSI
51
0.1u
0.1u
CD
10u
3.0k
68k
3300
p
68k
68k
560
p
0.18V
0.01u
100k
1000
p
SENSE
LEVEL
100k
10u
RSSI
COMP
QUAD DET
V+
CARRIER
SENSE
RSSI
OUT
FSK
OUT
V+
LPF
10u
CHARGE
IF AM P
FSK
COMP
NJM2590/97
Ver.2004-08-25
- 4 -
Test Circuit 1
S/N1, S/N2, Vin(lim), Vod, AMR
Test Circuit 2
DR
Test Circuit 3
Iccq
Test Circuit 4
Vrssi
Test Circuit 5
Ich
Test Circuit 6
VfskL
18
51
0.1u
S/N1, S/N2,
Vin(lim), Vod,
A
M
R
110
51
0.1u
V+
100
k
DR
214
A
V+
Iccq
111
51
0.1u
1000p
0.1u
4
Vrssi
V+
A
4
7 8
9
14
0.18
V
10u
Ich
V+
V
100u
A
10
VfskL
NJM2590/97
V
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5
-
Test Circuit 9
VcryL Test Circuit 10
Ilevel
Test Circuit 8
IcryH
Test Circuit 7
IfskH
V
100uA
V+
13
VcryL
V
100k
V+
10
IfskH = V/100k
12
SENSE
LEVEL
0.8V
A
Ilevel
V
100k
V+
13
IcryH = V/100k
NJM2590/97
Ver.2004-08-25
-
6
-
EVALUATION B OA RD
For obtaining actual performance data, an evaluation board is available. Note that this board is not prepared for the
reference design of parts layout, pattern layout and so on.
Circuit Diagram
CD: Ceramic discriminator, CDBCB455KCAY66-R0 (Murata manufacturing Co., Ltd.)
Circuit Board
V+
CARRIER SENSE
SENSE LEVEL
RSSI OUT
FSK OUT
FSK REF
IF IN
GND
GND
LPF OUT
123456 7
89
1011
12
1314
RSSI
0.1
0.1u CD
10u
3.0k
68k
3300
p
68k
68k
560
p
0.01u
100k
1000
p
100k
10u
RSSI
COMP
QUAD
V+
CARRIER
SENSE
RSSI
OUT
FSK
OUT
V+
LPF
10u
CHARGE
IF AMP
FSK
COMP
IF IN
SW
SENSE
LEVEL
LPF
OUT
FSK
REF
GND
NJM2590/97
V
er.2004-08-25 -7-
TERMINA L FUNCTION (Ta=25°C, V+=1.8V)
Pin No. SYMBOL EQUIVARENT CIRCUIT VOLTAGE FUNCTION
1 IF IN 1.75V
IF Amplifier Input.
Typical input impedance is
2kΩ.
Built in ESD protective
circuit.
3 DEC
1.75V
IF Decoupling.
Connected with an external
decoupling capacitor.
Built-in ESD protective
circuit
2 GND
--
Ground.
4 FSK REF
0.9V
FSK Reference Input.
This is a reference input of
wave shaping comparator.
Connected with an external
capacitor.
A quick charge/discharge
circuit offers the voltage of
pin 4 comes the same
voltage of pin 8 quickly.
Built-in ESD protective
circuit.
5 QUAD IN
0.5V
Quadrature Detector Input.
Connected with a ceramic
discriminator.
Built-in ESD protective
circuit.
6 AF OUT
0.2V
FM demodulated signal
output.
Built-in ESD protective
circuit.
3
1
V+
5
V+
6
V+
4
V+
NJM2590/97
Ver.2004-08-25
-
8
-
Pin No. SYMBOL EQUIVARENT CIRCUIT VOLTAGE FUNCTION
7 LPF IN 0.18V
Low Pass Filter Input.
This terminal is biased
from the pin 6 through an
external RC filter.
Built-in ESD protective
circuit.
8 LPF OUT
0.18V
Low Pass Filter Output.
Built-in ESD protective
circuit.
9 CHARGE
-
Quick Charge/Discharge
Control.
The power supply output
voltage to pin 9 sets up the
quick charge / discharge
circuit. Instead of the power
supply, another power
source can also be used
within the limit of the rated
supply voltage. Built-in
ESD protective circuit
between pin 9 and ground.
10 FSK OUT
-
FSK Output.
FSK comparator is a wave
shaping circuit.
A LPF output signal is
inverted and wave-shaped.
Instead of the power supply,
another power source can
also be used within the
limit of the rated supply
voltage. Built-in ESD
protective circuit between
pin 10 and ground.
11 RSSI OUT
50mV
Received Signal Strength
Indicator Output.
Pin 11 outputs DC level
proportional to the log of
input signal level to pin 1.
Built-in ESD protective
circuit.
7
8
V+
9
V+
10
V+
11
V+
NJM2590/97
V
er.2004-08-25 -
9
-
Pin No. SYMBOL EQUIVARENT CIRCUIT VOLTAGE FUNCTION
12 SENSE LEVEL
-
Sense Level Input.
Built-in ESD protective
circuit.
13 CARRIER
SENSE
-
Carrier Sense Output.
The result of RSSI
comparator is output by
comparing RSSI output
level with an external input
level to pin 12.
Built-in ESD protective
circuit between pin 13 and
ground.
14 V+
-
Power Supply.
12
V+
13
V+
14
NJM2590/97
Ver.2004-08-25
- 1
0
-
DESCRIPTION
1. FSK comparator (FSK COMP)
FSK comparator is a wave shaping circuit. When the demodulated FSK signal is weak or noisy, the computer may
fail to read this signal. To prevent the read-error, the wave shaping circuit will change this weak or noisy signal to the
correct signal. Pin 10 usually pulls up to power supply output voltage through an external high-valued resistor. This
external resistor can be connected to another power source within the limit of absolute maximum ratings.
2. Quick charge/ discharge circuit
The DC voltage of pin 4 is ordinarily equal to that of the demodulated FSK signal. When the initial state of power-up
turns into a steady state, the voltage of pin 4 will be late to come up to the reference voltage by reason of time
constant of an external capacitor and an internal resistor. At that time the wave shaped data may be failed to read
correctly. The quick charge/discharge circuit serves a useful function to shorten the rise time when power is turned
on. When power supply is hooked up to pin9 upon turning the power on, this circuit will charge/discharge the
external capacitor quickly to prevent read-error. Instead of the power supply, another power source can also be used
within the limit of the rated supply voltage.
During the high-speed charge/discharge circuit runs, DC level of FM demodulated signal may varies with frequency
shift or others. Even in such a case, the voltage of pin 4 follows the voltage of FM demodulated signal so that the
duty ratio of wave shaped output can keep constant.
9
300kΩ
4
V+
80kΩ
80kΩ
2.7kΩ
2kΩ
300Ω
+
-
48 10
10uF
300kΩ
300kΩ
100kΩ
V+
+
-
NJM2590/97
V
er.2004-08-25 -11-
3. Carri er sense
The result of comparator is output to pin13 by comparing the output voltage of pin11 with external reference voltage
of pin 12. Because pin13 is an open-collector terminal, an external resistor can be connected to another power
supply within the limit of absolute maximum ratings.
4. RSSI circuit (RSSI)
A DC voltage corresponding to the input level of pin1 is output to pin11. The internal resistance of pin11 is around 48
kΩ. The RSSI characteristics can be changed by adding an external resistor,. In such a case, note that the
temperature characteristics of pin 11 may alter due to a disparity between the temperature coefficient of the external
resistor and the internal resistor of pin 11.
5. Low pass filter (LPF)
This is a 3rd-order multiple feedback filter.
The cut-off frequency Fc is obtained by ;
where Ra=Rb=Rc or Ca=Cb=Cc
Each of pin7(LPF IN) and pin8(LPF OUT) has a built-in ESD protective resistor 300Ω.
11
1000pF Rext
V+
500Ω
300Ω
48kΩ
560pF
3300pF
6 7 8
0.01uF
300Ω
Ra Rb Rc
Ca Cb
Cc
300Ω
68kΩ68kΩ68kΩ
+
-
][
1
3
Hz
C
c
R
aRbRcCaC
b
Fc
=
2
π
11 13
12
1000pF SENSE
LEVEL 100kΩ
V+
+
-
NJM2590/97
Ver.2004-08-25
- 12 -
APPLICATION CIRCUIT
The NJM2590 itself works with the operational temperature from - 40 to +85°C. However this matter is not meant
to insure the reliability of this application circuit under the temperature from - 40 to +85°C.
CERAMIC DISCR IMINAT OR (especially designed for NJM2590/97)
To optimize some important performance, the following ceramic discriminator is available. For more information on
this CD and 450kHz CD, please contact the CD supplier.
CDBCB455KCAY66-R0 (Murata Manufacturing Co., Ltd., JAPAN)
1234 5 6 7
8
9
1011
12
1314
RSSI
0.1 0.1u
CD
10u
3.0k
68k
3300
p
68k
68k
560
p
0.01u
100k
1000
p
100k
10u
RSSI
COMP
QUAD
V+
CARRIER
SENSE
RSSI
OUT
FSK
OUT
V+
LPF
10u
CHARGE
IF AM P
FSK
COMP
IF IN
NJM2590/97
V
er.2004-08-25 -1
3
-
TYPICAL CHA RACTERI STICS
S+N,AMR ver sus Supply Vo ltage
0
10
20
30
40
50
60
70
0123456
Supply Voltage V+ (V)
S+R, AMR (dB)
AMR
(Vi=60dBuEMF, fin=455kHz, fmod=600Hz, fdev=±4kHz,Ta=25°C)
S+N
Demodulated Output versus Supply Voltage
0
10
20
30
40
50
60
70
80
0123456
Supply Voltage V+ (V)
Demodulated Output Vod (mVrms)
(Vi=60dBuEMF, fin=455kHz, fmod=600Hz, fdev=±4kHz,Ta=25°C)
Operating Current versus Supply Voltage
0
100
200
300
400
500
600
700
800
0123456
Supply Voltage V+ (V)
Operating Current Iccq (mA)
(No signal,Ta=25°C)
RSSI Output Voltage versus Supply Volgate
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0123456
Supply Voltage V+ (V)
RSSI Output Voltage Vrssi (V
)
(Vi=40dBuEMF, fin=455kHz, fmod=600Hz, fdev=±4kHz,Ta=25°C)
- 3dB Limiting Sensit ivity ver sus Supply Volt age
0
5
10
15
20
25
30
0123456
Supply Voltage V+ (V)
-3dB Limiting Sensitivit
y
Vin(lim) (dBuEMF)
(fin=455kHz, fmod=600Hz, fdev=±4kHz,Ta=25°C)
Duty Ratio of Wave Shaped Output versus Supply Voltage
40
42
44
46
48
50
52
54
56
58
60
0123456
Supply Voltage V+ (V)
Duty Ratio DR (%
)
Quick Charge ON
Quick Charge OFF
(Vi=60dBuEMF, fin=455kHz, fmod=600Hz, fdev=±4kHz,Ta=25°C)
NJM2590/97
Ver.2004-08-25
- 14 -
S+N, AMR versus IF Input Level
-80
-70
-60
-50
-40
-30
-20
-10
0
10
-20 0 20 40 60 80 100 120
IF Input Level Vin(dBuEMF)
S+N, AMR (dB)
N
S+N
AMR : AM=3 0 %
(Vi=60dBuEMF, fin=455kHz, fmod=600Hz, fdev=±4kHz,Ta=25°C)
S-Curve Characteristics
0
50
100
150
200
250
300
350
435 440 445 450 455 460 465 470
IF Input Frequency fin (kHz)
AF Output Voltage (mV)
60dBuVEMF
25dBuVEMF
(Vi=60dBuEMF, fmod=600Hz, fdev=±4kHz,Ta=25°C)
IF Detuning Characteristics
-30
-25
-20
-15
-10
-5
0
5
-15 -10 -5 0 5 10 15
Relative Frequency to fin (kHz)
Detuning (dB)
60dBuVEMF
25dBuVEMF
(Vi=60dBuEMF, fin=455kHz, fmod=600Hz, fdev=±4kHz,Ta=25°C)
Carr ier Sens e O ut put Char act e r istics
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
00.511.52
RSSI Output Voltage Vrssi (V)
Carrier Sense Output Voltage
Vcry (V)
(fin=455kHz, fmod=600Hz, fdev=±4kHz,Sense Level=0.8V,Ta=25°C)
Quick Charge/Discharge Cur ren t vers us
FSK Ref e r e nc e Inpu t Volt a ge
-80
-60
-40
-20
0
20
40
60
80
0 100 200 300 400 500
FSK Reference Input Voltage (mV)
Quick Charge/ Di s char ge C urrent (uA)
(No input signal,Ta=25°C)
RSSI Output Level versus IF Input Leve l
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-20 0 20 40 60 80 100 120
IF Input Level Vi (dBuEMF)
RSSI Output Voltage Vrssi (V)
(fin=455kHz, fmod=600Hz, fdev=±4kHz,Ta=25°C)
NJM2590
NJM2597
NJM2590/97
V
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5
-
Operat ing C urr ent versus Amb ient Temperatur e
0
100
200
300
400
500
600
700
800
900
1000
-40 -20 0 20 40 60 80 100
Ambient Temperature Ta(°C)
Operating Current Iccq(mA)
(No input signal,V+=1.8V)
-3dB Li m i tin g S e n si tivi ty versus Am bi e n t Te m p e rature
0
5
10
15
20
25
30
35
40
-40 -20 0 20 40 60 80 100
Ambient Temperature Ta(°C)
-3dB Limiting Sensitivity
Vin(lim) (dBuEMF)
(fin=455kHz, fmod=600Hz, fdev=±4kHz,V+=1.8V)
S +N versus Amb ien t Temp erature
0
10
20
30
40
50
60
70
80
-40-20 0 20406080100
Ambient Temperature Ta (°C)
S+N S/N1,S/N2(dB)
S/N1: Vi=60dBuEMF
S/N2: Vi=25dBuEMF
(fin=455kHz, fmod=600Hz, fdev=±4kHz,V+=1.8V)
Dem o dul ated Output L evel versus Ambi ent Temper ature
0
10
20
30
40
50
60
70
80
90
100
-40-20 0 20406080100
Ambient Temperature Ta (°C)
Demodulated Output Level
Vod (mVrms)
(Vi=60dBuEMF,fin=455kHz, fmod=600Hz, fdev=±4kHz,V+=1.8V)
AM Rejection Ra tio ve rsus Ambi ent Te m pera ture
0
10
20
30
40
50
60
70
80
-60 -40 -20 0 20 40 60 80 100
Ambient Temperature Ta (°C)
AM Rejection Ratio AMR (dB
)
(AM<30%, fin=455kHz, fmod=600Hz, fdev=±4kHz,V+=1.8V)
Duty Ratio of Wave Shaped Output versus Ambient Temperature
40
42
44
46
48
50
52
54
56
58
60
-40 -20 0 20 40 60 80 100
Ambient Temperature Ta (°C)
Duty Ratio of Wave Shaped outpu
t
DR (%)
(Vi=60dBuEMF,fin=455kHz, fmod=600Hz, fdev=±4kHz,V+=1.8V)
NJM2590/97
Ver.2004-08-25
- 1
6
-
[CAUTION]
The specifications on this databook are only
given for information , without any guarantee
as regards either mistakes or omissions. The
application circuits in this databook are
described only to show representative usages
of the product and not intended for the
guarantee or permission of any right including
the industrial rights.
Quick Charge/DischargeCurr ent versus Ambient Temperature
0
10
20
30
40
50
60
70
80
90
100
-40-20 0 20406080100
Ambient Temperature Ta (°C)
Quick Charge/Discharge Current
Ich (uA)
(V
FSKOUT
=GND, V
LOFOU T
=0.18V,V+=1.8V)
RSSI Output Resistance versus Ambient Temperature
0
10
20
30
40
50
60
-40 -20 0 20 40 60 80 100
Ambient Temperature Ta (°C)
RSSI Output Resistance (kΩ)
(Vi=40dBuEMF,fin=455kHz, fmod=600Hz, fdev=±4kHz,V+=1.8V)
RSSI Output V oltage versus Am bient Temperature
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
-40-20 0 20 406080100
Ambient Temperature Ta (°C)
RSSI Output Voltage Vrssi (V)
1.6V
1.8V
3.0V
5.0V
(Vi=40dBuEMF,fin=455kHz, fmod=600Hz, fdev=±4kHz,V+=1.8V)
