Ordering number : EN1140D Monolithic Linear IC LA1143 FM IF System for Car Radios Overview Package Dimensions The LA1143 is an IF system IC designed for FM car stereo receivers. It features versatile muting characteristics and allows receiver designers to realize the muting performance according to their design concept. Since the muting characteristics can be varied with a switch or a semi-fixed resistor, DX-Local switching will be accomplished with ease. unit: mm 3006B-DIP16 [LA1143] Functions • IF amplification/limiter • AF preamplifier • Signal meter output • Muting at detuning • Quadrature detector • AFC output • AGC output • Muting at small input SANYO: DIP16 Features 1. Versatile mutings a) When muting operation is performed under a weak signal strength, an attenuation slope of the audio output against the input signal strength variations can be set at any given value. b) Maximum muting attenuation can be selected to be approximately 6 to 40dB. c) Input signal strength level which actuates the muting circuit can be set freely. 2. High limiting sensitivity (25 dBµ typ. with muting off) provides a good quieting characteristic. 3. High S/N (78dB typ.) 4. Low distortion (0.05% typ.) available, if used with double-tuned circuits. 5. Good AMR (63dB with 6 stages of differential IF amplifiers). 6. Signal meter drive output proportional to the input signal strength in dB (suitable to control multiplex IC LA3373). 7. Clamped (±VBE) AFC output, bandwidth adjustable. 8. Delayed AGC output for front end circuit. Equivalent Circuit Block Diagram SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN 91297HA (KT)/D157KI/2126KI/5085MW/D142KI, TS No.1140-1/5 LA1143 Specifications Maximum Ratings at Ta=25°C Parameter Symbol Conditions Ratings Unit Maximum supply voltage VCC max Pin 12 16 V Maximum supply current ICC max 40 mA Allowable power dissipation Pd max Ta=25°C 640 mW Ta=70°C 460 mW ±1 Vp-p Pin 12 Input voltage VIN Pin 1 to 2 Flow-in current I2 Pin 2 ±0.2 mA I3 Pin 3 ±0.2 mA I6 Pin 6 2 mA I5 Pin 5 1 mA I13 Pin 13 2 mA I14 Pin 14 2 mA I15 Pin 15 1 mA I16 Pin 16 Flow-out current 1 mA Operating temperature Topr –20 to +70 °C Storage temperature Tstg –40 to +125 °C Operating Condition at Ta=25°C Parameter Symbol Recommended supply voltage VCC Operating voltage range VCC op Conditions Ratings Unit 8 V 7.5 to 16 V Operating Characteristics at Ta=25°C, VCC=8V, f=10.7MHz, See specified Test Circuit. Parameter Symbol Conditions Ratings min typ max Unit Quiescent current ICCO Quiescent 15 21 27 mA Current drain ICC VIN=100dBµ 20 25 30 mA Demodulation output VO VIN=100dBµ,400Hz, 100% mod. Total harmonic distortion THD VIN=100dBµ,400Hz, 100% mod. Signal to noise ratio S/N VIN=100dBµ,400Hz, 100% mod. Input limiting voltage VIN(lim) VO : 3dB down, 400Hz 100% mod. Muting sensitivity VIN(mute) V14=2.0V Muting attenuation (1) Mute(ACC) V6=2.0V (22kΩ), VIN=100dBµ, 400Hz 100% mod. Muting attenuation (2) Mute(ACC) V6=5.0V (22kΩ), VIN=100dBµ, Muting bandwidth BW(mute) AM rejection ratio AMR 200 260 320 mVrms 0.05 0.2 % 25 29 dBµ 22 26 35 dBµ 10 15 20 dB 24 28 32 dB 140 210 370 kHz 50 63 3.5 4.2 5.0 V 0 0 0.3 V 72 78 dB 400Hz 100% mod. VIN=100dBµ, V14=2.0V VIN=100dBµ, FM 400Hz 100% mod. dB AM 1kHz 30% mod. Muting drive output V14-0 Quiescent Muting drive output V14-100 VIN=100dBµ Signal meter output (1) V15-0 Quiescent Signal meter output (2) V15-50 VIN=50dBµ Signal meter output (3) V15-70 VIN=70dBµ Signal meter output (4) V15-100 VIN=100dBµ AGC output (1) V16-0 Quiescent 3.5 4.1 4.5 V AGC output (2) V16-100 VIN=100dBµ 0 0.02 0.3 V Offset voltage (1) V7-13 Quiescent, pin 7 to 13 –0.25 0 +0.25 V Offset voltage (2) V8-13 Quiescent, pin 8 to 13 –0.5 0 +0.5 V 0 0.1 0.3 V 0.8 1.4 2.0 V 1.6 2.4 3.2 V 4.5 5.3 6.0 V No.1140-2/5 LA1143 AC Test Circuit T1 : CBTKAC-24782AUO (Toko Co.) T2 : CBTKAE-24783X (Toko Co.) 22µH : S-220J (Korin Co.) Input signal strength is an actual input at pin 1. Unit (resistance : Ω, capacitance : F) Muting Characteristic The muting operation in the LA1143 is performed by an AF preamplifier, the gain of which varies continuously with control current, and a muting drive circuit which supplies the control current. The gain of th AF preamplifier decreases with increasing gain control current applied to pin 6. However, the gain does not decrease further when the control current reaches approximately 120µA or more. The lower limit of the gain under this condition depends upon a resistor connected between the pin 5 and GND, and the higher the resistance the lower the gain (the higher the attenuation). Thus the maximum muting attenuation will be set by connecting the resistor between the pin 5 and GND. Since the muting control input pin 6 is connected to the base of the emitter-grounded transistor (through a protection resistor of 500Ω in series), the voltage between pin 6 and GND is about 0.6V when the control current is applied. In actual cases, the muting operation is accomplished by applying a voltage drive type muting drive output (pin 14) to pin 6 through a high resistance (up to 20kΩ). Unit (resistance : Ω) The muting drive output comes in three types : 1) Hole detector output which develops a voltage when C/N (carrierto-noise ratio) lowers under weak signal input condition. 2) A reversed output of the signal strength indicating output (output at pin 15). 3) A bandwidth limited muting drive output which develops a voltage when the AFC output becomes higher than ±VBE during detuning operation. All these outputs are led to an OR circuit and the processed output is developed at pin 14. Of the above muting drive outputs, descriptions on the hole detector output and the bandwidth limited muting drive Continued on next page. No.1140-3/5 LA1143 Continued from preceding page. output will be omitted, since they are the same as those used in conventional quadrature detector ICs ( such as LA1230, LA1231N). The inverted output of the signal strength indication output is obtained as illustrated below. By referring to the illustration, V14 is given by the formula : V14=Vr–(I0+I1–aI2)RL–VBE. Conditions are : Vr≈4.9V, I0≈0.2mA, a≈2, RL=22kΩ, VBE≈0.6V, I1=V15/R15-G, I2=V16/R16-G, where V16 is a constant equal to 4.1V (typ.) for medium or lower signal input levels, where the muting drive output is required. Since the V15 increases proportionally to the increase of the input signal strength, I1 will also increase. Therefore the V14 will decrease with increasing signal strength. Thus the required muting drive output can be obtained by selecting proper values of R15-G and R16-G. For example, the muting drive output moves toward strong input signal level if th R16-G is decreased, or the muting drive output becomes zero due to the offset current IO under a weak signal input condition, if the R16-G is increased to infinity (namely pin 16 is opened). However the muting drive output caused by a hole detector still exists in this case. In creasing R15-G decreases the slope of the curve for the muting drive output vs. antenna signal input level, or decreasing the R15-G increases the slope of the curve. Furthermore, varying the value of a resistor connected between the muting drive output (pin 14) and the muting control input (pin 6) changes the value of the muting control current required to obtain the same muting drive output, accordingly a slope of curve for muting attenuation vs. antenna signal input level is also changed. These characteristics investigated by using an actual receiver are shown on the curves below. The general method to adjust the muting circuit of the LA1143 is : to set the signal input level required to actuate the muting circuit with the R16-G, to adjust the slope of the curve for the muting attenuation vs. antenna signal input with the R15-G, and to adjust the maximum muting attenuation (determined by setting the noise level at no signal) with the R5-G. The slope of the curve for the muting attenuation vs. antenna signal input level can also be adjusted by the resistor connected between pins 14 and 6 in addition to R15-G, however, selecting a resistor too high does not allow the muting control current flowing into pin 6 to reach 120µA even though the maximum muting drive output (V14) is applied, namely the muting attenuation does not reach its maximum value. Accordingly a recommended value of the resistor between pins 14 and 6 is about 22kΩ. No.1140-4/5 LA1143 Muting by varying R15-G Allowable power dissipation, Pd max – mW Pd max – Ta Ambient temperature, Ta – °C Muting by varying R14-6 Proper cares in using LA1143 1. The detector transformers should be designed to develop a quadrature signal (pin 11) of higher than 175mVrms (about 105dBµ) under high antenna signal input. If the quadrature signal strength is less than 125mVrms, the muting drive output can not decrease to zero even in a strong signal strength. Furthermore, when the quadrature signal strength lies between 125mV and 175mV, the muting drive output may move from zero to plus under high temperature conditions. 2. Do not connect a capacitor directly between pin (16) and ground. If the signal intensity of IF input varies in the vicinity of 90dBµ, the voltage at pin (16) varies. Thus, charging/discharging current flows into the capacitor and goes to the muting drive output (pin (14)) through the inverter inside the IC, thereby causing the muting to malfunction. For detailed data and sample application circuits, refer to the catalog of the LA1140. No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace equipment, nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of which may directly or indirectly cause injury, death or property lose. Anyone purchasing any products described or contained herein for an above-mentioned use shall: Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors and all their officers and employees, jointly and severally, against any and all claims and litigation and all damages, cost and expenses associated with such use: Not impose any responsibilty for any fault or negligence which may be cited in any such claim or litigation on SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees jointly or severally. Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of intellectual property rights or other rights of third parties. This catalog provides information as of September, 1997. Specifications and information herein are subject to change without notice. No.1140-5/5