Audio ICs 1.5V FM/AM IF system IC BA4230AFS The BA4230AFS is an AM/FM IF system IC that operates off a 1.5V power supply. The FM circuit consists of a differential IF amplifier, a double-balance quadrature detector, and a weak input-signal IF mute circuit. The AM circuit consists of a local oscillator, a double-balance mixer circuit, an IF amplifier, a detector circuit, and an AGC circuit. The IC also has a built-in LED driver circuit for AM/FM tuning indication. @ Applications 1.5V headphone HiFi stereo equipment. @Features 1) Excellent jow-voltage operating characteristics 6) Provision for connection of a low-pass filter for (0.9V min., 1.0 to 2.0V recommended), AM operation. 2) Two system outputs to enable both upper- and 7) Switch between AM and FM bands by switching lower-heterodyne AFC operation. the DC power on and off. 3) Built-in FM muting to reduce naise between sta- 8) One output for both AM and FM, allows connec- tions when tuning and noise when the input signal tion to a MPX without a switch. is weak. 9) Built-in driver circuit for an AM/FM tuning indica- 4) Quadrature circuit for FM demodulation. tor LED, and forced monaural operation for weak 5) AM oscillator, mixer, and detector circuits built-in. FM signals is possible. 10) Suitable for use with the BA1362F 1.5V FM stereo multiplexer. @Block diagram BA4230AFS E Ly AM oscL2| Ig]GND AM Voc [3] ia)LeD AM ANT IN[4 4 H7JAGC AM MIX OUT[E 4 HJAM FILTER end [6] ia]FM MUTE AM IF INT? 4 & L{i4jar our T > FM IF IN[e|-+ 5 | 3 {13 AF OUT = = ald Ss L ramp Bypass[aH 2] | || 2 | [vec vu QO IF AMP ByPASS[IO}-} : FM DET COIL 71 IF systerrs High-frequency signal processorsAudio ICs BA4230AFS @Absolute maximum ratings (Ta = 25) Parameter Symbol Limits Unit Supply voltage Vec (Max.) 2.5 Vv Power dissipation Pg 600 * mw Operating temperature Topr 25~75 c Storage temperature Tstg 55~125 ie; * Reduced by 6mW for each increase in Ta of 1C over 25C. @Recommended operating conditions (Ta == 25C) Parameter Symbol Min. Typ. Max. Unit Supply voltage Vec 1.0 1.25 2.0 Vv @ Electrical characteristics FM (Unless otherwise specified, Ta = 25C and Veo = 1.25V, fin = 10.7MHz, fm = 400Hz, Af = 22.5kHz, and Vin = 1000B x V) Parameter Symbol Min, Typ. Max. Unit Conditions Quiescent current la _ 7 8.5 mA Mute off, no input Detector output Vo 40 55 70 mMVims | Vin=100dB ue V Total harmonic distortion THD - 0.2 0.6 % Vin=100dB ye V Signal-to-noise ratio S/H 56 60 _ dB Vin=1000B ne V -3dB limiting sensitivity VIN (im) 33 36 39 dB eV | Vour=3dB LED sensitivity VL 41 46 51 dB eV | iL=1mA Mute off sensitivity Ve 50 54 58 dB pV _ @ Electrical characteristics AM (Unless otherwise specified, fw = 1000kKHz, fm = 400Hz, MOD = 30% and Vin = 1000B ye V} Parameter Symbol Min Typ. Max. Unit Conditions Quiescent current la _ 5.5 7.6 mA No input Detector output Vo 35 45 55 mMVins | Vin=740B eV Total harmonic distortion THD _ 1.0 2.0 % Vin=74cB pV Signal-to-noise ratio SIN 44 48 - dB Vin=740B pV Sensitivity 5 10 15 _ dB eV | Vo=10mVrmns LED sensitivity Vi 14 18 22 dByeV | l=1mA 72 ROMAudio ICs BA4230AFS @Measurement circuit Viep a "" e 7 soon 20H for hotue 10 nF 3009 aF al 22 0.022 eae (GeO Toot we [eo] [io] fiel 7] ffiel [is BA42a0AFS pie shat p22, 00 oF yr ye sari o* AM/FM 760 Ty AM OSC 4177-216(SUMIDA} Tp | AM IFT 4176-352(SUMIDA) Ty: FM DET 4176-208(SUMIDA) CF, 7 AM CERAMIC FILTER(PF&455) MURATA) FM SG: Fig.1 @Application example AM ANT a Vigo o VT Fi 001 wre as wie AF 3309 FM ANT Tz GF; T 0.022 uF fe ! a l I Ft 0.082 FS 100pF 7e~1oaMt: [2 6 934 of, Tae 121 4. 1 FMFRONTEND 1! na CO 8 FM AM IF BA4408F a BA4230AFS \ oot 1 3 400k0 OFF 1 ON aN Mure to CHECK 1 ooa7 ae uF ap T, | AM OSC 4117-216(SUMIDA} CF, CF, | FM SFE10.7MA5 (MURATA) Tg | AMIFT 4175-352(SUMIDA} OF | AM PFB455, (MURATA) Tg} FM DET 4176-208(8UMIDA) Fig.2 RBM 78 IF systems High-frequency signal processorsAudio ICs BA4230AFS Circuit operation (1) AM/FM amplifier The IF amplifier consists of a differential amplifier with input impedance set by a ceramic filter. The input im- pedance is set to about 3009 for FM, and about 2k Q for AM. The circuit switches between the AM and FM bands when the current to the first-stage amplifier is switched on and off. , FM IF IN AMIF IN 8 7 o Veo To next amplifier Ho owe BIAS s000 2kQ BIAS oo 99 1 FM AM l 0.022 y 1 i KF Fig. 3 (2) FM detector and output circuits The FM detector uses a quadrature detector circuit. The output resistance is about 5k 2, and the DC out- put voltage is approximately 0.6V (1VF). Mute operates on the pin 14 output, but not the pin 13 output. AM output is from pin 14 only. ~L Voo or GND AF OUT 0.01 pF 014 FM IF Fig. 4 (3) FM mute circuit The FM mute circuit switches the output resistance on and off depending on the magnitude of the FM IF level. When the the IF level is small, it decreases the audio output. To switch muting off, connect pin 15 to GND. FM IF 14 AF OUT LEVEL DET Fig. 5 (4} AM local oscillator and mixer The AM oscillator is a differential circuit. The primary side of the coil is connected to ground, and the sec- ondary side is connected between pin 2 and the AM VCC. The AM mixer uses a double-balance circuit. The input from the antenna goes to pin 4 via a capacitor, and the mixer output is output from pin 5 to the ITF. AM ANT ET, OokuF 2 AM OSG o5e 8 e? a aT ye F at a" AM Vg Fig. 6 (5) AM detector and AGC circuits The AM detector is a differential circuit. The detector output is high-cut by the circuit formed by the internal 1kQ@ resistor, and the capacitor connected to pin 16. This high-cut detector goes through the AF amplifier, and is output on pin 14 (the AM detector output is not output from pin 13). The DC output level of the detector is fed into the AGC circuit which controls the mixer circuit and the IF am- plifier gain. 74 NemAudio ICs BA4230AFS (6) AM/FM tuning indicator LED drive circuit and ap- plication circuits This circuit can be used to drive a tuning indication LEO. In this case, however, you must provide a sepa- rate power supply of at least 2V. To reduce stereo noise when receiving weak FM sig- nals, it is possible to force the following FM multiplexer (eg. BA1362F) into monaural operation using the out- put from pin 18. The pin 18 output has about 1dB of hysteresis. @Coil specitications . (1) FM IFT(10.7MHz)4176-303(P-5LG) (SUMIDA) AM/FM tuning indicator circuit Forced-monaural operation circuit (for weak signals} BA1362F SYNC DET, CO BA4230AF Fig. 8 4-6 4t ve Ic--43 4t-cr 3-2 11t 2 2-1 3 Voo-{1 6+~GND GND - Ic AM Voc Wire type 0.09UEW C=82pF az40 (2) FM DET(10.7MHz)4176-208(P-5LG) (SUMIDA) CF - GND I-43 o4 1-3 13t Ie+4 3 AM Voo~ c 1 06 Wire type C.09UEW C=100pF Q=50 (3) AM OSC(796kHz)4177-216(P-5LG) (SUMIDA) 3 4 i 1 6 (4) AM IFT(455kHz)4175-352(P-5LG) (SUMIDA) 6-4 8t 1-3 1131 Wire type 0.05JEW L=250 H Q250 6-4 26 3-2 98 2-1 60t Wire type O.04UEW C=180pF Q235 75 mm IF systems High-frequency signal processorsAudio ICs BA4230AFS @ Electrical characteristic curves 12 10 | FM AM | L_ QUIESCENT CURRENT | Ig (mA) D> Fig. 9 Quiescent current vs. power TOTAL HARMONIC DISTORTION: THD (3%) Fig. 12 Total harmonic distortion (FM) vs. power supply voltage OUTPUT VOLTAGE : Vout (V) 560 AMBIENT TEMPERATURE : Ta (0) Fig. 15 FM detector output voltage vs. 0.5 1 1.6 2 2.5 SUPPLY VOLTAGE : Veco () supply voltage f= 10.7MHz MOD=400Hz DEV=309%% Vin=800B pV 05 1 1.6 2 25 SUPPLY VOLTAGE: Veo (V) Veco=1.25 t=10.7MHz MOD=400Hz DEV=30% Vi HY ~25 60 25 50 75 ambient temperature 1=10,7MHz Voc=1,26V S MOD=400Hz S f=10,.7MHz a DEV=309% 31 MOD=400Hz s VouT=3dB g DEV=30%% 80 z E 2 > E 5 wm 60 = = lu Ww wn wn 40 g Q z z = 5 = 20 a a 8 o 8 66506106ClU1506lU2 2G 8 50 -25 0 2 50 75 100 SUPPLY VOLTAGE: Vcc (V} AMBIENT TEMPERATURE : Ta (C) Fig. 10 FM limiting sensitivity vs. Fig. 11 FM limiting sensitivity vs. power supply voltage ambient temperature = 120 8 Voo=1.25 f=10,.7MHz a f=10.7MHz MOD=400Hz & MOD=400Hz = 100 DEV=30% z DEV=30% v & Vin=80d8 pV = # > ao = 2 Ee w & g 2 = 60 a z | 2 > 2 ZL 40 2 5 : E + 3 20 a = zg 9 a -50 -25 0 2 50 78 100 0 OF 1 #15 2 25 3 AMBIENT TEMPERATURE : Ta (C) SUPPLY VOLTAGE : Veo (Vv) Fig, 13 Total harmonic distortion (FM) Fig. 14 FM detector output voltage vs. vs. ambient temperature power supply voltage 4 40 Veo=125V 9 Voo=1 25V {=10,.7MHz _ f=10.7MHz a 20 MOD=400Hz a 20 MOD=400Hz 2 DEF=30% ~ DEV=30% 5 MUTE. OFF Bg MUTE ON 8 / SN = S+N wi Wu G Q 20 20 = A = 5 3 /| > _ 40 \ * 40 = = Ee o = ao 3-80 Pa 5 20 N N oS N ao 0 0 20 40 60 80 8100 6120 INPUT VOLTAGE : Vy (Bu) Fig. 16 FM detector output voltage vs. input voltage (mute off) 0 20 40 60 80 100 86120 INPUT VOLTAGE : Vy (dB Vv) Fig. 17 FM detector output voltage vs. input voltage (mute on) 76Audio ICs BA4230AFS a i 40 Vec==1.25V a f=10,7MHz %S 20 MOD : fra FM 400Hz30%% 2 6 AM 1kHz3096 2 Ee z 20 Qo 2 S| o~40 Ww wo oO =~ 60 t a0 o 20 40 60 80 100 120 INPUT VOLTAGE ! Viy (By) Fig. 18 FM AM rejection ratio vs. input voltage mr Vec=1,25V =1000kHz 5 MOD=460Hz DEV=30% Vin =800B yu ro \ 50 -25 9 25 50 76 100 AMBIENT TEMPERATURE : Ta {C} TOTAL HARMONIC DISTORTION : THD (3%) o Fig. 21 Total harmonic distortion (AM} vs. ambient temperature Vec=1.25V t=1000kHz MOD=400Hz DEV=30% 500 S+N | 8 QUTPUT VOLTAGE : Vgyq (dB) i 2 o 2 40 60 80 100 120 INPUT VOLTAGE : Viq (By) Fig. 24 AM detector output voltage vs. input voltage 60 {=1000kHz 7 MOD=400Hy = DEV=30% = Vig 808 jc 3 a / > % / 2 30 | 3 * 29 bE Zz E 2 10 Ol OUTPUT VOLTAGE : Vou, (dB) Vec=1.25V f=10.7MHz Vinn= 80dB ye V MOD=400Hz a - TOTAL HARMONIC DISTORTION : THD{%} co o 29 40 60 a0 1000 (120 DEVIATION : DEV (kHz} Fig. 19 Total harmonic distortion (FM) vs. modulation 9 0.5 1 1.5 2 2.5 3 SUPPLY VOLTAGE : Vec () Fig. 22 AM detector output voltage vs. power supply voltage a 6 Vec=1.25 {=1000kHz MOD=400Hz DEV=309% Qa S+N 60 80 Q 2049 260COBDsCdTNDSCd2 INPUT VOLTAGE : Viy (dB V) Fig. 25 AM detector output voltage vs. input voltage f=1000MHz MOD=400Hz DEV=30% Vi=B00B u V an TOTAL HARMONIG DISTORTION ! THD (9%) ~~ 0 o5 1 45 2 25 3 SUPPLY VOLTAGE ; Veco () Fig. 20 Total harmonic distortion (AM} vs. power supply voltage 60 Vec=1,25V f=1000kHz 50] MOD=4o0gHz an DEV=30% Lee gq | f= 80e8 Vee th [=] OUTPUT VOUTAGE : Vou (mv) -50 -25 0 26 50 75 = 100 AMBIENT TEMPERATURE : Ta (C) Fig. 23 AM detector output voltage vs. ambient temperature ~ 12 s Voc=1.25V o 1=1000kHz E 10 Mod frequency . 400Hz & 3 tkHz E Vin =80dB pV 5 I I a 6 MOD=400Hz ] Q Fa z AK =, Ao | tkHZ z se Po o 20064006 660 OBOC100s120 MODULATION: MOD (34) Fig. 26 Total harmonic distortion (AM} vs. modulation 77 IF systems High-frequency signal processorsAudio ICs BA4230AFS @External dimensions (Unit: mm) a7t0.2 20 11 AR ARAAR RRR a| 2 +H) 4 rn aL | BEBBBEEEEE co 1 10 4 =! 4 5 2 {Ge > 2 ra I 5 OB 0.95+0.1 | oan \ Tos) SSOP-A20 78 nanmNotes The contents described in this catalogue are correct as of March 1997. No unauthorized transmission or reproduction of this book, either in whole or in part, Is permitted. The contents of this book ara subject to change without notice. Always verify before use that the contents are the latest specifications. If, by any chance, a defect should arise in the equipment as a result of use without verification of the specifications, ROHM CO., LTD., can bear no responsibility whatsoever. Application circuit diagrams and circuit constants contained in this data book are shown as examples of standard use and operation. When designing for mass production, please pay careful attention to peripheral conditions. Any and all data, including, but not limited to application circuit diagrams, information, and various data, described in this catalogue are intended only as illustrations of such devices and not as the specifications for such devices. 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