NJM2537 FM IF IC FOR PAGERS ■ GENERAL DESCRIPTION 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 ● Low Operating Current ● RF Input Frequency ● 2nd Mixer ● Package Outline ■PACKAGE OUTLINE NJM2537V 1.1 to 4.0V 1.2mA typ.at V+=1.4V 10 to 50MHz SSOP20 ■ PIN FUNCTION AND BLOCK DIAGRAM 1. 2. 3. 4. 5. 6. 7. 8. 9 10. Ver.2003-12-09 OSC IN OSC OUT MIXER OUT V+ IF IN DECOUPLING FSK REF QUAD IN AF OUT RSSI 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. LPF IN LPF OUT BS CHARGE FSK OUT VALM REG CONT REG OUT GND MIXER IN -1- NJM2537 ■ ABSOLUTE MAXIMUM RATINGS PARAMETER (Ta=25°C) 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 PARAMETER (V+=1.4V, fC=21.7MHz, fIF=455kHz, fmod=600Hz, fdev=±4kHz, Ta=25°C) SYMBOL TEST CONDITION MIN. TYP. MAX. UNIT No Signal Operating Current ICCq - 1.2 1.5 mA Battery Saving ICCS - 0 5 µA 11 14.5 18 dB IP - 103 - dBµVEMF Mixer Input Resistance RinMIX - 5 - kΩ Mixer Output Resistance ROMIX - 2 - kΩ RinIF - 2 - kΩ Operating Current Mixer Gain Mixer Intercept Point IF Amplifier Input Resistance GMIX After Ceramic Filter S/N1 S/N1 MIXER Input, VI=60dBµVEMF - 63 - dB S/N2 S/N2 IF Input, VI=60dBµVEMF - 63 - dB S/N3 S/N3 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 40 70 115 µA 1.05 1.10 1.15 V Quick Charge / Discharge Current Ich GND, 0.18V Alarm Detection Voltage Valm 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 - 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 - - 0.6 V -2- IL=100µA IL=100µA Ver.2003-12-09 NJM2537 ■ APPLICATION CIRCUIT Ver.2003-12-09 -3- NJM2537 ■ TERMINAL FUNCTION PIN NO. 1 2 SYMBOL OSC IN OSC OUT PIN VOLTAGE (V) FUNCTION 1.38 Local Oscillator Input. In case of using a crystal oscillator, it is connected. 0,68 EQUIVALENT CIRCUIT Local Oscillator Output. In case of using an external oscillator, the external clock is input. Mixer input. Input resistance is 5kΩ typical. 20 MIX IN 0.8 Mixer output. Output resistance is 2kΩ typical. 3 5 MIX OUT IF IN 0.7 1.38 Limiter amplifier input. Input resistance is 2kΩ typical. Decoupling for bias. 6 8 DEC QUAD IN 1.38 1.4 Input of quadrature detection circuit. A ceramic discriminator is connected. Demodulated signal Output. 9 -4- AF OUT 0.16 Ver.2003-12-09 NJM2537 ■ TERMINAL FUNCTION PIN NO. SYMBOL PIN VOLTAGE (V) FUNCTION EQUIVALENT CIRCUIT RSSI output 10 RSSI 0 Input of a low pass filter. It is biased from AF-OUT (9pin) through an external RC filter. 11 LPF IN 0.18 Output of a low pass filrter. 12 7 LPF OUT FSK REF 13 14 15 BS CHARGE FSK OUT Ver.2003-12-09 0.18 0.18 - - - Reference input of a wave shaping comparator. An external capacitor is connected. Control of a battery saving circuit. Hi : active Lo : suspended Control of a quick charge / discharge circuit. Hi : Its circuit turns ON Lo : Its circuit turns OFF Output of a wave shaping circuit. The output signal is inverted against LPF output signal. -5- NJM2537 ■ TERMINAL FUNCTION PIN NO. SYMBOL PIN VOLTAGE (V) FUNCTION EQUIVALENT CIRCUIT Output of the alarm signal. + When V drops down to 1.1V, this output becomes high. 16 VALM 0.1 Control of an external PNP transistor used for the regulator. 17 REG CONT 0.6 Monitoring of the regulator. 18 REG OUT 4 V - Power Supply - 19 GND - Ground - -6- + 1.0 Ver.2003-12-09 NJM2537 ■ TYPICAL CHARACTERISTICS S+N N, AMR vs. Mixer Input V + = 1.4 V, fRF = 21.7MHz, fLO = 22.155MHz VLO = 110dBuV, fdev = ±4kHz, f mod = 600Hz S+N, N, AMR vs. IF Input (V+=1.4V, fIF=455kHz, fdev=±4kHz, fmod=600Hz) Mixer Gain vs. Supply Voltage (fin=21.7MHz, VRF=60dBuV, fLO=22.155MHz, VLO=110dBu) Operating Current vs. Supply Voltage (No Signal) RSSI vs. Supply Voltage (VIF=65dBuVEMF, fIF=455kHz) Demodulated Output vs. Supply Voltage (Vin=60dBuVEMF, fIF=455kHz, fmod=600Hz) Ver.2003-12-09 -7- NJM2537 ■ TYPICAL CHARACTERISTICS Quick Charge Current vs. Supply Current (12pin=0.18V) Operating Current vs. Temperature (V+=1.4V) Battery Saving Operating Current vs. Temperature (V+=1.4V) Quick Charge Current vs. Temperature (V+=1.4V, 12pin=0.18V) Mixer Gain vs. Temperature (V =1.4V, fRF=21.7MHz, Vin=60dBµV) Demodulated Output vs. Temperature (V =1.4V, fIF=455kHz, Vin=60dBµVEMF, fmod=600Hz) + -8- + Ver.2003-12-09 NJM2537 ■ TYPICAL CHARACTERISTICS RSSI vs. Temperature V + = 1.4 V, fRF21.7MHz, VRF = 50dBuVEMF, fLO = 22.155MHz, VLO = 110dBuV, mod = OFF -3dB Limiting Sensitivity vs. Temperature (V+=1.4V, Mixer input, fRF=21.7MHz, fmod=600Hz) Mixer Output vs. RF Input (V+=1.4V, fRF=21.7MHz, fLO=22.155MHz, VLO=110dBuV) Mixer Gain vs. Local Oscillation V + = 1.4V, fRF = 21.7MHz, VRF = 60dBuV, fLO = 22.155MHz, V = 60dBuV in Mixer Gain vs. Frequency (V+=1.4V, VRF=60dBuV, VLO=110dBuV, fLO=fRF+455kHz) RSSI vs. IF Input (V+=1.4V, fIF=455kHz) Ver.2003-12-09 -9- NJM2537 [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. - 10 - Ver.2003-12-09