SANYO LA3370 Datasheet

Ordering number : EN619H

Monolithic Linear IC

LA3370

PLL FM Multiplex Stereo Demodulator

for Car Stereo

	Overview	Package Dimensions
	The LA3370 is a multiplex IC for FM car stereo, and it has	unit: mm
	the following 2 functions through its utilization of the IF	3020A-SIP16
	meter output voltage, etc.
	1. Stereo noise control (SNC) under which the noise	[LA3370]
	particular to the FM stereo unit in the weak electric
	field is reduced smoothly.

2.High-cut control (HCC) under which the high frequency is smoothly attenuated. In additioin, the LA3370 can be, due to its low distortion factor, an IC for multiplex stereo demodulator which is appropriate for the car component stereo unit.

Functions

SANYO: SIP16

•Stereo noise control (SNC terminal)

Through controlling the quality of sound from stereo mode to monaural mode with the voltage applied to the control pin, the FM stereo noise in the weak electric field is reduced by this function.

•High-cut control function (HCC terminal)

The FM noise in the weak electric field is reduced through the attenuation of high frequency thereof.

Such attenuation can be changed smoothly from "Normal" to "High Cut" by controlling the voltage applied to the control pin. The volume of "High Cut" can be selected by using an external capacitor.

•Stereo-monaural automatic select

This selection has priority over the stereo noise control. Pilot input prioritized.

•Stoppage of VCO oscillation

When a voltage of 7.5V or higher is applied to the HCC terminal, the oscillation of VCO can be discontinued. In this case, the stereo lamp does not malfunction.

•With separation control terminal.

Features

•Low distortion factor. (0.05% typ. 300mV input, mono)

•The ripple of power source can effectively be rejected. (35dB typ.)

•The range of voltage to be used is wide. (VCC=6.5 to 14V)

•The space factor is advantageous because of the single-end package.

•The printed circuit board can easily be prepared as 3mm pitch is used between the pins.

SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters

TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN

63097HA (KOTO) / 8288YT/3018TA/5205MW, TS No.619-1/11

LA3370

Specifications

Maximum Ratings at Ta=25°C

Parameter	Symbol	Conditions		Ratings			Unit
Maximum supply voltage	VCCmax					16	V
Lamp driving current	IL					40	mA
Allowable power dissipation	Pd max	Ta≤ 45°C				520	mW
Operating temperature	Topr			–20 to +70			°C
Storage temperature	Tstg			–40 to +125			°C
Recommended Operating Conditions at Ta=25°C
Parameter	Symbol	Conditions		Ratings			Unit
Recommended supply voltage	VCC			6.5 to 14			V
Input signal voltage	VIN			200 to 300			mV
Operation Characteristics	at Ta=25°C,	VCC=10V, VIN=300mV, f=1kHz,	L+R=90%, pilot=10%
	See specified Test Circuit.
Parameter	Symbol	Conditions		Ratings			Unit
			min	typ		max
Quiescent current	Icco			21		27	mA
Channel separation	Sep		40	50			dB
Monaural distortion	mono THD	Mono=300mV		0.05		0.2	%
Stereo distortion	ST THD	Main		0.05		0.2	%
Lamp turning-on level	VL	L+R=90%, pilot=10%	60	85		120	mV
Hysteresis	hy			3		6	dB
Capture range	CR	Pilot=30mV		±3			%
Output signal level	VO	Sub	140	200		280	mV
S/N ratio	S/N		70	78			dB
Input resistance	ri			20			kΩ
SCA rejection	SCArej			80			dB
Allowable input voltage	VIN	THD=1%	700	800			mV
SNC output attenuation	Att SNC	V8=0.6V, L–R=90%, pilot=10%	–8.5	–3.0		–0.3	dB
SNC output voltage	VO sub	V8=0.1V, L–R=90%, pilot=10%				5	mV
HCC output attenuation	Att HCC 1	V7=0.6V, L+R=90%, pilot=10%	–15.0	–6.0		–0.5	dB
	Att HCC 2	V7=1V, L+R=90%, pilot=10%	–2.0			0	dB
Power ripple rejection	Rr			35			dB
VCO stopping voltage	VCO stop			6.8			V
Channel balance	CH Ba			0.5		1.5	dB

Test Circuit

No.619-2/11

LA3370

Sample Application Circuit and Equivalent Circuit Block Diagram

SNC (stereo noise control) and HCC (high-cut control)

The LA3370 has SNC and HCC terminals for improved S/N ratios when operating in weak radio fields. By adjusting the SNC terminal, noises unique to stereo FM in weak fields can be reduced. The HCC terminals permits further improvement of effective S/N ratios by lowering treble levels of FM noises in weak fields. (See Fig.2)

STEREO deteriorates approximately 21.7dB (compared to MONO) in weak radio fields (Fig.2). Generally, when S/N ratios deteriorate below 30 to 40dB, noises become quite noticeable. Section (1) shows ways to set SNC and HCC when radio field strengths are divided into 3 regions, A, B, and C (Fig.2). SNC is expected to function in region A, and HCC in region B. In region C, shallow muting is effected in the IF stage.

No.619-3/11

LA3370

(1)SNC (stereo noise control)

Stereo S/N ratios deteriorate 21.7dB below monaural but can be improved by varying stereo separation. S/N improvement becomes apparent, however, only when the separation is 20dB or worse. In that case, the relation between separation and S/N improvement is shown in Fig.3.

SNC in the LA3370 improves S/N ratios in weak radio fields by varying separation. It varies subsignal demodulation level and controls separation. By using the IF stage signal meter level output as the source of the control signal, S/N ratios in region A of Fig.2 can be maintained at about 40dB or better. Ideal S/N enhancements should provide gradual switching over from stereo to monaural to maintain constant S/N ratios, starting from a point in region A for 40dB stereo S/N toward a point for 40dB monaural S/N. Methods to set the control level will be described later.

Fig.4 shows voltages applied to pin 8 (SNC terminal) of LA3370 versus separation characteristics (SNC characteristics). Pin 8 is also the base of a PNP transistor, so stereo mode is set when pin 8 is open and monaural mode is set when it is grounded. SNC terminal control is effective only when locked with pilot signals and when stereo indicator is lit. External circuit parameters can be chosen in large values that do not affect the IF stage meter output circuit because SNC control currents are small. This makes designing easy. (See Fig.5)

(2)Designing external circuits for SNC characteristics (characteristic setting by drawing)

We recommend the following as a way to adjust SNC characteristics to have smooth transition of separation from stereo monaural in region A of Fig.2.

Separation vs. S/N enhancement relation……………………… Refer to Fig.3. SNC pin voltage vs.separation characteristics………………… Refer to Fig.4.

Antenna inputs vs. S/N improvement characteristics can be obtained from the drawing if the graph for IF stage signal meter output vs. antenna input and the graph for stereo S/N ratio vs. antenna input are known. From desired S/N characteristics, SNC terminal voltage characteristics can also be obtained. Sample drawings are shown in Fig.6, where for simplicity's sake, SNC, IF meter, and stereo S/N characteristics have been approximated with straight lines.

For instance :

To obtain stereo S/N improvement characteristics from SNC characteristics, when (a) in the second quadrant of the chart represents bare SNC characteristics, point 1 projected to the third quadrant shows a 20dB separation and a 1dB S/N improvement. When projected from the first to the fourth quadrant, a point improved by 1dB in S/N over the stereo S/N line in the fourth quadrant corresponds to point 1. Similarly, point 2 on the SNC characteristics in the second quadrant corresponds to point 2 in the fourth quadrant. Point 3 in the second quadrant corresponds to point 3 in the fourth quadrant. Stereo S/N improvement characteristics for each point are obtainable. Similarly, (b) characteristics in the second quadrant are projected to form (b) characteristics in the fourth quadrant, and (c) in the second quadrant to form (c) in the fourth quadrant, thus providing a way to diagram improvement characteristics.

In the resulting drawings, ideal S/N improvement characteristics are similar to (b) in the fourth quadrant, but corresponding SNC characteristics have to be (b) characteristics in the second quadrant which are difficult to realize. Among realistic characteristics, something like (c) appears to be satisfactory. The (c) SNC characteristics are obtained with a shift by two diodes together with a 1/2 bleeder.

No.619-4/11