NJM2537
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Ver.2003-12-09
FM IF IC FOR PAGERS
■ GENERAL DESCRIPTION ■PACKAGE OUTLINE
The NJM2537 is a low power FM IF IC for pagers.
It is capable of designing dual conversion pager system because
of including a mixer circuit. Also it includes RSSI function, so that it is
easy to design automatic gain control (AGC) which improves
interberence when strong signal is received.
■ FEATURES
● Low Operating Voltage 1.1 to 4.0V
● Low Operating Current 1.2mA typ.at V+=1.4V
● RF Input Frequency 10 to 50MHz
● 2nd Mixer
● Package Outline SSOP20
■ PIN FUNCTION AND BLOCK DIAGRAM
1. OSC IN 11. LPF IN
2. OSC OUT 12. LPF OUT
3. MIXER OUT 13. BS
4. V+ 14. CHARGE
5. IF IN 15. FSK OUT
6. DECOUPLING 16. VALM
7. FSK REF 17. REG CONT
8. QUAD IN 18. REG OUT
9 AF OUT 19. GND
10. RSSI 20. MIXER IN
NJM2537V
NJM2537
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■ ABSOLUTE MAXIMUM RATINGS (Ta=25°C)
PARAMETER SYMBOL RATINGS UNIT
Supply voltage VCC 4.0 V
Power Dissipation PD 300 mW
Operating Temperature Range Topr -30 to +85 °C
Storange Temperature Range Tstg -40 to +125 °C
■ ELECTRICAL CHARACTERISTICS (V+=1.4V, fC=21.7MHz, fIF=455kHz, fmod=600Hz, fdev=±4kHz, Ta=25°C)
PARAMETER SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT
No Signal Operating Current ICCq - 1.2 1.5 mA
Battery Saving ICCS - 0 5 µA
Operating Current Mixer Gain GMIX After Ceramic Filter 11 14.5 18 dB
Mixer Intercept Point IP - 103 - dBµVEMF
Mixer Input Resistance RinMIX - 5 - kΩ
Mixer Output Resistance ROMIX - 2 - kΩ
IF Amplifier Input Resistance RinIF - 2 - kΩ
S / N 1 S / N 1 MIXER Input, VI=60dBµVEMF - 63 - dB
S / N 2 S / N 2 IF Input, VI=60dBµVEMF - 63 - dB
S / N 3 S / N 3 IF Input, VI=22dBµVEMF - 25 - dB
-3dB Limiting Sensitivity 1 LIM1 MIXER Input - 12 17 dBµVEMF
-3dB Limiting Sensitivity 2 LIM2 IF Input - 22 27 dBµVEMF
Demodulated Output Level Vod IF Input, VI=60dBµVEMF 30 46 65 mVrms
AM Rejection Ratio AMR IF Input, VI=60dBµVEMF, AM=30% - 50 - dB
Duty Ratio at Wave Shaped Output DR IF Input, VI=60dBµVEMF 40 50 60 %
RSSI Output Voltage Vrssi IF Input, VI=65dBµVEMF 0.48 0.62 0.76 V
RSSI Output Resistance Rrssi - 62 - kΩ
Quick Charge / Discharge Current Ich GND, 0.18V 40 70 115 µA
Alarm Detection Voltage Valm 1.05 1.10 1.15 V
Regulator Output Voltage Vreg RL=430Ω 0.95 1.00 1.05 V
Low level Output Voltage
of VALM Terminal ValmL IL=100µA - 0.1 0.4 V
High Level Leak Current
of VALM Terminal IalmH - 0 2 µA
Low Level Output Voltage
of FSK-OUT Terminal VfskL IL=100µA - 0.1 0.4 V
High Level Leak Current
of FSK-OUT Terminal IfskH - 0 2 µA
Low Level Output Voltage
of REG-OUT Terminal VregL IL=100µA - - 0.6 V
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■ APPLICATION CIRCUIT
NJM2537
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■ TERMINAL FUNCTION
PIN NO. SYMBOL PIN VOLTAGE (V) FUNCTION EQUIVALENT CIRCUIT
1 OSC IN 1.38
Local Oscillator Input.
In case of using a crystal
oscillator, it is connected.
2 OSC OUT 0,68
Local Oscillator Output.
In case of using an external
oscillator, the external clock is
input.
20 MIX IN 0.8
Mixer input.
Input resistance is 5kΩ typical.
3 MIX OUT 0.7
Mixer output.
Output resistance is 2kΩ
typical.
5 IF IN 1.38
Limiter amplifier input.
Input resistance is 2kΩ typical.
6 DEC 1.38
Decoupling for bias.
8 QUAD IN 1.4
Input of quadrature detection
circuit.
A ceramic discriminator is
connected.
9 AF OUT 0.16
Demodulated signal Output.
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■ TERMINAL FUNCTION
PIN NO. SYMBOL PIN VOLTAGE (V) FUNCTION EQUIVALENT CIRCUIT
10 RSSI 0
RSSI output
11 LPF IN 0.18
Input of a low pass filter. It is
biased from AF-OUT (9pin)
through an external RC filter.
12 LPF OUT 0.18
Output of a low pass filrter.
7 FSK REF 0.18
Reference input of a wave
shaping comparator.
An external capacitor is
connected.
13 BS -
Control of a battery saving
circuit.
Hi : active
Lo : suspended
14 CHARGE -
Control of a quick charge /
discharge circuit.
Hi : Its circuit turns ON
Lo : Its circuit turns OFF
15 FSK OUT -
Output of a wave shaping
circuit. The output signal is
inverted against LPF output
signal.
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■ TERMINAL FUNCTION
PIN NO. SYMBOL PIN VOLTAGE (V) FUNCTION EQUIVALENT CIRCUIT
16 VALM 0.1
Output of the alarm signal.
When V+ drops down to 1.1V,
this output becomes high.
17 REG CONT 0.6
Control of an external PNP
transistor used for the
regulator.
18 REG OUT 1.0
Monitoring of the regulator.
4 V+ - Power Supply -
19 GND - Ground -
NJM2537
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Ver.2003-12-09
■ TYPICAL CHARACTERISTICS
S+N N, AMR vs. Mixer Input S+N, N, AMR vs. IF Input
=±==
===
+
Hz600modf,kHz4fdev,dBuV110VLO
MHz155.22fLO,MHz7.21fRF,V4.1V
(V+=1.4V, fIF=455kHz, fdev=±4kHz, fmod=600Hz)
Mixer Gain vs. Supply Voltage Operating Current vs. Supply Voltage
(f
in
=21.7MHz, VRF=60dBuV, fLO=22.155MHz, VLO=110dBu)
(No Signal)
RSSI vs. Supply Voltage Demodulated Output vs. Supply Voltage
(VIF=65dBuVEMF, fIF=455kHz) (Vin=60dBuVEMF, fIF=455kHz, fmod=600Hz)
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■ TYPICAL CHARACTERISTICS
Quick Charge Current vs. Supply Current Operating Current vs. Temperature
(12pin=0.18V) (V+=1.4V)
Battery Saving Operating Current vs. Temperature Quick Charge Current vs. Temperature
(V+=1.4V) (V+=1.4V, 12pin=0.18V)
Mixer Gain vs. Temperature Demodulated Output vs. Temperature
(V+=1.4V, fRF=21.7MHz, Vin=60dBµV) (V+=1.4V, fIF=455kHz, Vin=60dBµVEMF, fmod=600Hz)
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■ TYPICAL CHARACTERISTICS
RSSI vs. Temperature -3dB Limiting Sensitivity vs. Temperature
===
==
+
OFFmod,dBuV110VLO,MHz155.22fLO
,dBuVEMF50VRF,MHz7.21fRF,V4.1V
(V+=1.4V, Mixer input, fRF=21.7MHz, fmod=600Hz)
Mixer Output vs. RF Input Mixer Gain vs. Local Oscillation
(V+=1.4V, fRF=21.7MHz, fLO=22.155MHz, VLO=110dBuV)
==
===
+
dBuV60V,MHz155.22fLO
,dBuV60VRF,MHz7.21fRF,V4.1V
in
Mixer Gain vs. Frequency RSSI vs. IF Input
(V+=1.4V, VRF=60dBuV, VLO=110dBuV, fLO=fRF+455kHz) (V+=1.4V, fIF=455kHz)
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[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.
