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Ordering number : EN1140D
Monolithic Linear IC
LA1143
FM IF System for Car Radios
Overview
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.
Package Dimensions
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 dB 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=25C
Parameter Maximum supply voltage Maximum supply current Allowable power dissipation Input voltage Flow-in current Symbol VCC max Pin 12 ICC max Pd max VIN I2 I3 I6 Flow-out current I5 I13 I14 I15 I16 Operating temperature Storage temperature Topr Tstg Pin 12 Ta=25C Ta=70C Pin 1 to 2 Pin 2 Pin 3 Pin 6 Pin 5 Pin 13 Pin 14 Pin 15 Pin 16 Conditions Ratings 16 40 640 460 1 0.2 0.2 2 1 2 2 1 1 -20 to +70 -40 to +125 Unit V mA mW mW Vp-p mA mA mA mA mA mA mA mA C C
Operating Condition at Ta=25C
Parameter Recommended supply voltage Operating voltage range Symbol VCC VCC op Conditions Ratings 8 7.5 to 16 Unit V V
Operating Characteristics at Ta=25C, VCC=8V, f=10.7MHz, See specified Test Circuit.
Parameter Quiescent current Current drain Demodulation output Total harmonic distortion Signal to noise ratio Input limiting voltage Muting sensitivity Muting attenuation (1) Muting attenuation (2) Muting bandwidth AM rejection ratio Muting drive output Muting drive output Signal meter output (1) Signal meter output (2) Signal meter output (3) Signal meter output (4) AGC output (1) AGC output (2) Offset voltage (1) Offset voltage (2) Symbol ICCO ICC VO THD S/N VIN(lim) VIN(mute) Quiescent VIN=100dB VIN=100dB,400Hz, 100% mod. VIN=100dB,400Hz, 100% mod. VIN=100dB,400Hz, 100% mod. VO : 3dB down, 400Hz 100% mod. V14=2.0V 22 10 24 140 50 3.5 0 0 0.8 1.6 4.5 3.5 0 -0.25 -0.5 72 Conditions Ratings min 15 20 200 typ 21 25 260 0.05 78 25 26 15 28 210 63 4.2 0 0.1 1.4 2.4 5.3 4.1 0.02 0 0 5.0 0.3 0.3 2.0 3.2 6.0 4.5 0.3 +0.25 +0.5 29 35 20 32 370 max 27 30 0.2 Unit mA mA % dB dB dB dB dB kHz dB V V V V V V V V V V
320 mVrms
Mute(ACC) V6=2.0V (22k), VIN=100dB, 400Hz 100% mod. Mute(ACC) V6=5.0V (22k), VIN=100dB, 400Hz 100% mod. BW(mute) AMR V14-0 V14-100 V15-0 V15-50 V15-70 V15-100 V16-0 V16-100 V7-13 V8-13 VIN=100dB, V14=2.0V VIN=100dB, FM 400Hz 100% mod. AM 1kHz 30% mod. Quiescent VIN=100dB Quiescent VIN=50dB VIN=70dB VIN=100dB Quiescent VIN=100dB Quiescent, pin 7 to 13 Quiescent, pin 8 to 13
No.1140-2/5
LA1143 AC Test Circuit
T1 : CBTKAC-24782AUO (Toko Co.) T2 : CBTKAE-24783X (Toko Co.) 22H : S-220J (Korin Co.) Input signal strength is an actual input at pin 1.
Unit (resistance : , 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 120A 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 500 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 20k). 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
Unit (resistance : )
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 : Vr4.9V, I00.2mA, a2, RL=22k, VBE0.6V, 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 120A 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 22k.
No.1140-4/5
LA1143
Pd max - Ta Allowable power dissipation, Pd max - mW
Muting by varying R15-G
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 105dB) 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 90dB, 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

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