LA1787M-MPB-E_技术文档

LA1787M

Specifications

Maximum Ratings at Ta = 25°C

Parameter

Symbol

Conditions

Ratings

Unit

V

_CC1 max

_CC2 max

Pins 6, 40, and 61

9

12

Maximum supply voltage

V

Pins 7, 45, 54, 59, and 60

V

Allowable power dissipation

Operating temperature

Storage temperature

Pd max

Topr

Ta ≤ 55°C

950

mW

°C

–40 to +85

Tstg

–40 to +150

Operating Conditions at Ta = 25°C

Parameter

Symbol

V_CC

_CCST IND Pin 26

_CCop

Conditions

Ratings

Unit

V

Pins 6, 7, 40, 45, 54, 59, 60, and 61

8

5

Recommended supply voltage

Operating supply voltage range

V

7.5 to 9.0

V

Operating Characteristics at Ta = 25°C, V = 8.0V, in the specified test cricuit for the FM IF input

CC

Ratings

unit

Parameter

Symbol

Conditions

min

typ

max

[FM Characteristics] At the FM IF input

Current drain

I

_CCO-FM

No input, I40 + I45 + I54 + I59 + I60 + I61

60

205

190

–1

94

310

295

0

110

415

380

+1

mA

mVrms

dB

Demodulation output

Pin 31 demodulation output

Channel balance

V_O-FM

10.7 MHz, 100dBµ, 1 kHz, 100%mod, The pin 15 output

10.7 MHz, 100dBµ, 1 kHz, 100%mod, The pin 31 output

The ratio between pins 15 and 16 at 10.7 MHz, 100 dBµ, 1 kHz

V_O-FM31

CB

Total harmonic distortion

Signal-to-noise ratio: IF

AM suppression ratio: IF

THD-FM mono 10.7 MHz, 100 dBµ, 1 kHz, 100% mod, pin 15

0.3

82

1

%

S/N-FM IF

AMR IF

10.7 MHz, 100 dBµ, 1 kHz, 100% mod, pin 15

75

55

dB

10.7 MHz, 100 dBµ, 1 kHz, f_m= 1 kHz, 30% AM, pin 15

68

dB

10.7 MHz, 100 dBµ, 1 kHz. The pin 15

attenuation when V33 goes from 0 to 2 V

Att-1

Att-2

5

10

20

33

40

15

25

38

dB

10.7 MHz, 100 dBµ, 1 kHz. The pin 15

attenuation when V33 goes from 0 to 2 V^*1

Muting attenuation

Separation

15

28

30

10.7 MHz, 100 dBµ, 1 kHz. The pin 15

attenuation when V33 goes from 0 to 2 V^*2

Att-3

10.7 MHz, 100 dBµ, L+R = 90%, pilot = 10%. The pin 15 output

ratio

Separation

Stereo on level

ST-ON

ST-OFF

The pilot modulation such that V26 < 0.5 V

1.2

0.6

2.4

1.6

0.3

4.4

1.2

%

Stereo off level

The pilot modulation such that V26 > 3.5 V

Main total harmonic distortion

THD-Main L

10.7 MHz, 100 dBµ, L+R = 90%, pilot = 10%. The pin 15 signal

10.7 MHz, 100 dBµ, pilot = 10%.

The pin 15 signal/the pilot level leakage. DIN audio

Pilot cancellation

PCAN

AttSNC

20

1

30

5

dB

10.7 MHz, 100 dBµ, L-R = 90%, pilot = 10%.

V28 = 3 V → 0.6 V, pin 15

SNC output attenuation

9

10.7 MHz, 100 dBµ, 10 kHz, L+R = 90%, pilot = 10%.

V29 = 3 V → 0.6 V, pin 15

AttHCC-1

AttHCC-2

0.5

6

4.5

10

8.5

14

HCC output attenuation

10.7 MHz, 100 dBµ, 10 kHz, L+R = 90%,

pilot = 10%. V29 = 3 V → 0.1 V, pin 15

100 dBµ, 10.7 MHz, 30% modulation. The IF input such

that the input reference output goes down by 3 dB

Input limiting voltage

Muting sensitivity

Vi-lim

Vi-mute

33

27

54

40

35

62

47

43

70

dBµ

The IF input level (unmodulated) when V33 = 2 V

The IF input level (unmodulated) (over 100 mV rms)

such that the IF counter buffer output goes on

SD-sen1 FM

SD sensitivity

SD-sen2 FM

V_IFBUFF-FM

54

130

0.0

62

200

0.1

70

270

0.3

dBµ

IF counter buffer output

10.7 MHz, 100 dBµ, unmodulated. The pin 23 output

No input. The pin 24 DC output, unmodulated

50 dBµ. The pin 24 DC output, unmodulated

70 dBµ. The pin 24 DC output, unmodulated

100 dBµ. The pin 24 DC output, unmodulated

100 dBµ. The bandwidth when V33 = 2 V, unmodulated

100 dBµ, 0 dBµ. The pin 33 DC output, unmodulated

mVrms

V

_SMFM-1

V

V_SMFM-2

0.4

1.0

1.5

Signal meter output

V

_SMFM-3

_SMFM-4

2.0

2.7

3.5

V

4.7

5.5

6.2

V

Muting bandwidth

Mute drive output

BW-mute

V_MUTE-100

150

0.00

220

0.03

290

0.20

kHz

V

Continued on next page.

No. 6655-2/54

LA1787M

Continued from preceding page.

Ratings

typ

unit

Parameter

[FM FE Mixer Input

N-AGC on input

Symbol

Conditions

min

max

83 MHz, unmodulated.

V_N-AGC

V_WAGC

81

88

95

dBµ

The input such that the pin 2 voltage is 2.0 V or below

83 MHz, unmodulated. The input such that the pin 2

voltage is 2.0 V or below. (When the keyed AGC is set to 4.0 V.)

W-AGC on input

104

110

116

Conversion gain

A.V

83 MHz, 80 dBµ, unmodulated. The FE CF output

No input

19

85

30

48

mVrms

Oscillator buffer output

[NC Block] NC input (pin 30)

Gate time

V_OSCBUFFFM

110

165

τGATE1

f = 1 kHz, for a 1-µs, 100-mV p-o pulse

55

40

µs

The level of a 1 = kHz, 1-µs pulse input that starts

noise canceller operation. Measured at pin 30.

Noise sensitivity

SN

mVp-o

The pulse rejection effect provided by the noise canceller.

For a repeated 1-µs wide pulse, frequency = 10 kHz,

150 mV p-o. The ratio of the FM mode pin 15 output

referenced to the AM mode pin 15 output (effective value)

NC effect

SN-NC

5

[Multipath Rejection Circuit] MRC input (pin 27)

MRC output

VMRC

V24 = 5 V

2.2

10

2.3

15

2.4

20

V

The pin 32 input level at f = 70 kHz such that

pin 24 goes to 5 V and pin 27 goes to 2 V

MRC operating level

MRC-ON

mVrms

[AM Characteristics] AM ANT input

Practical sensitivity

S/N-30

V_O-AM

1 MHz, 30 dBµ, f_m= 1 kHz, 30% modulation, pin 15

1 MHz, 74 dBµ, f_m= 1 kHz, 30% modulation, pin 15

1 MHz, 74 dBµ, f_m= 1 kHz, 30% modulation, pin 31

20

dB

Detector output

130

110

195

175

270

230

mVrms

mVms

Pin 31 detector output

V_O-AM31

1 MHz, 74 dBµ, referenced to the output, the input amplitude

such that the output falls by 10 dB. Pin 15

AGC F.O.M.

V_AGC-FOM

51

47

56

61

dB

Signal-to-noise ratio

S/N-AM

1 MHz, 74 dBµ, f_m= 1 kHz, 30% modulation

1 MHz, 74 dBµ, f_m= 1 kHz, 80% modulation

No input

52

0.3

0.2

6

dB

%

Total harmonic distortion

THD-AM

1

V

_SMAM-1

_SMAM-2

0.0

4.8

185

92

0.5

7.3

V

Signal meter output

1 MHz, 130 dBµ, unmodulated

V

Oscillator buffer output

Wide band AGC sensitivity

V_{OSCBUFF AM1}No input, the pin 15 output

230

98

mVrms

dBµ

mVrms

W-AGCsen1

W-AGCsen2

SD-sen1 AM

SD-sen2 AM

V_IFBUFF-AM

1.4 MHz, the input when V46 = 0.7 V

104

95

1.4 MHz, the input when V46 = 0.7 V (seek mode)

83

89

1 MHz, the ANT input level such that the IF counter output turns on.

1 MHz, the ANT input level such that the SD pin goes to the on state.

1 MHz, 74 dBµ, unmodulated. The pin 23 output

24

30

36

SD sensitivity

24

30

36

IF buffer output

200

290

Note: These measurements must be made using the either the IC-51-0644-824 or KS8277 IC socket (manufactured by Yamaichi Electronics).

* 1. When the resistor between pin 58 and ground is 200 kΩ.

* 2. When the resistor between pin 58 and ground is 30 kΩ.

No. 6655-3/54

LA1787M

Function List

FM Front End (Equivalent to the Sanyo LA1193)

• Double input type double balanced mixer

• Pin diode drive AGC output

• MOSFET second gate drive AGC output

• Keyed AGC adjustment pin

Multiplex Functions

• Adjustment-free VCO circuit

• Level follower type pilot canceller circuit

• HCC (high cut control)

• Automatic stereo/mono switching

• VCO oscillation stop function (AM mode)

• Forced monaural

• Differential IF amplifier

• Wide band AGC sensitivity setting pin, and narrow

band AGC sensitivity setting pin

• Local oscillator

• SNC (stereo noise controller)

• Stereo display pin

• Anti-birdie filter

FM IF

• IF limiter amplifier

AM

• S-meter output (also used for AM) 6-stage pickup

• Multipath detection pin (shared FM signal meter)

• Quadrature detection

• Double balanced mixer (1st, 2nd)

• IF amplifier

• Detection

• AF preamplifier

• RF AGC (narrow/wide)

• AGC output

• Pin diode drive pin

• Band muting

• IF AGC

• Weak input muting

• Signal meter output (also used for FM)

• Local oscillator circuits (first and second)

• Local oscillator buffer output

• IF counter buffer output (also used by the FM IF)

• SD (IF counter buffer on level) adjustment pin

• SD output (active high) (also used for AM)

• Wide AGC

• Soft muting adjustment pin

• Muting attenuation adjustment pin

• IF counter buffer output (also used for AM)

• SD (IF counter buffer on level) adjustment pin

• SD output (active high) (also used for AM)

Noise Canceller

• Detection output frequency characteristics

adjustment pin (low cut, high deemphasis)

• AM stereo buffer

• High-pass filter (first order)

• Delay circuit based low-pass filter (fourth order)

• Noise AGC

• Pilot signal compensation circuit

• Noise sensitivity setting pin

• Function for disabling the noise canceller in AM

mode

MRC (multipath noise rejection circuit)

AM/FM switching output (linked to the FM V

)

CC

No. 6655-4/54

LA1787M

Operating Characteristics and Symbols Used in the Test Circuit Diagrams

Switches (SW)

Switch on = 1, SW off = 0

There are two switches that use signal transfer.

— SW2: switches between the mixer input and the IF input.

— SW4: switches between noise canceler input and IF output + noise canceler input.

Types of SG used

PG1 (AC1) Used for noise canceler testing. A pulse generator and an AF oscillator are required.

AC2

AC3

AC4

AC5

Used for FM front end testing. Outputs an 83 MHz signal.

Used for FM IF, noise canceler, and MPX testing. Outputs a 10.7 MHz signal. Stereo modulation must be possible.

Used for AM testing. Outputs 1 MHz and 1.4 MHz signals.

Used with the MRC. Can also be used for AF and OSC.

Power supply

V_CC

8 V

V

_CC1

5 V

SD, stereo, seek/stop

Keyed AGC, Mute ATT

HCC, SNC, SASC (MRC)

_CC2

_CC3

0.1 V / 0.7 V / 2 V / 4 V

0.1 V / 0.6 V / 2 V

These levels

must be variable.

• Switches

Parameter

ON

FM

OFF

AM

SW1

SW2

SW3

SW4

SW5

SW6

SW7

SW8

SW9

AM/FM switching. The FE V_CCis supplied to pin 62.

FM IF switching. Pin 51/FE output

For conversion gain testing

FE IF OUT (A)

AC3 (B)

Conversion gain measurement (A)

AC1 (A)

Other/purposes

Seek (IF buffer output)

OFF

For switching between noise canceler input and IF output + noise canceler.

High-speed SD

STOP

SEEK/STOP (IF BUFF ON/OFF)

MUTE ATT 200 kΩ

MUTE 200 kΩ

MUTE ATT 30 kΩ

MUTE 30 kΩ

OFF

For pilot cancellation testing

When pilot cancellation is used

MUTE OFF

When pilot cancellation is not used

MUTE ON

SW10 Mute off (pin 33)

• Trimmers (variable resistors)

VR1

VR2

Separation adjustment

Pilot cancellation adjustment

Test Points

• DC voltages

VD1

VD2

VD3

VD4

VD5

VD6

VD7

FM RF AGC voltage

Pin 2

AM/FM SD, AM Tweet, FM stereo indicator Pin 26

AM/FM S-meter

Pin 24

Pin 27

Pin 33

Pin 46

Pin 8

MRC output

Mute drive output

AM antenna damping voltage

N.C. Gate time

• AC voltages

VA1

VA2

VA3

VA4

VA5

AM/FM OSC Buff

Pin 4

First IF output

Pin 53 → CF → pin 51 load level (10.7 MHz)

Pin 23 (10.7 MHz/450 kHz)

Pin 15 (AF)

IF counter buffer

MPX OUT Left ch

MPX OUT Right ch

Pin 16 (AF)

No. 6655-5/54

LA1787M

Pin Descriptions

Pin No.

Function

Description

Equivalent circuit

V

62 pin

CC

ANT

RF

AGC

1000pF

An antenna damping current flows

when the RF AGC voltage (pin 2)

reaches V_CC– V_D.

300Ω

100Ω

1

Antenna damping drive

100Ω

1

1000pF

A13555

V

CC

FET

2nd GATE

12kΩ

2

+

Used to control the FET

second gate.

2

RF AGC

DAMPING

DRIVER

ANT

N

W

AGC

DET

AGC

DET

V

CC

KEYED

AGC

A13556

3

F.E.GND

V

CC

4

OSC

Oscillator connection

25pF

20pF

2kΩ

V

T

A13557

7

V

CC

AM first oscillator

This circuit can oscillator up to the

SW band.

7

AM OSC

An ALC circuit is included.

A L C

A13558

Continued on next page.

No. 6655-6/54

LA1787M

Continued from preceding page.

Pin No.

Function

Description

Equivalent circuit

3kΩ

15kΩ

After setting up the medium field

(about 50 dBµ) sensitivity with the

noise sensitivity setting pin (pin 8),

set the weak field (about 20 to

30 dBµ) sensitivity with the AGC

adjustment pin (pin 9)

200Ω

8

9

Noise AGC sensitivity

AGC adjustment

8

9

3kΩ

+

0.47µF

1MΩ

0.01µF

A13559

0.01µF

6800pF

3.9kΩ

13

12

11

V

CC

11

12

Recording circuit used during

noise canceller operation.

Memory circuit connection

Differential

amp

Gate

circuit

LPF

A13560

V

CC

30kΩ

PLL

13

Pilot input

Pin 13 is the PLL circuit input pin.

N.C

12

13

0.01µF

A13561

Ground for the N.C., MPX, and

MRC circuits.

14

N.C, MPX, MRC, GND

Continued on next page.

No. 6655-7/54

LA1787M

Continued from preceding page.

Pin No.

Function

Description

Equivalent circuit

V

CC

Deemphasis

50 µs: 0.015 µF

75 µs: 0.022 µF

15

16

MPX output (left)

MPX output (right)

3.3kΩ

15

16

0.015µF

A13562

V

CC

20kΩ

10kΩ

Adjustment is required since the

pilot signal level varies with the

sample-to-sample variations in

the IF output level and other

parameters.

6.7kΩ

17

Pilot canceller signal output

17

18

0.01µF

100kΩ

A13563

V

CC

Pin 18 is the output pin for the

pilot canceller signal.

18

Pilot canceller signal output

1.5kΩ

17

18

0.01µF

100kΩ

A13564

Continued on next page.

No. 6655-8/54

LA1787M

Continued from preceding page.

Pin No. Function

Description

Equivalent circuit

DECODER

5kΩ

Composite

signal

4kΩ

Use a trimmer to adjust the

subdecoder input level.

Separation

adjustment pin

19

(The output level is not modified in

mono and main modes.)

19

30kΩ

0.047µF

A13565

CSB

912

JF108

20

V

REF

20

VCO

The oscillator frequency is 912 Hz.

KBR-912F108

10pF

(Kyocera Corporation)

CSB-912JF108

(Murata Mfg. Co., Ltd.)

A13566

V

REF

15kΩ

21

22

PHASE COMP.

+

19kΩ

21

22

A13567

Continued on next page.

No. 6655-9/54

LA1787M

Continued from preceding page.

Pin No. Function

Description

Equivalent circuit

+

–

4.9V

AM MUTE

50kΩ

10kΩ

+

–

1.3V

IF counter

buffer

V

CC

This pin functions both as the IF

counter buffer (AC output) and as

the seek/stop switch pin.

The voltage V23 switches

between the following three

modes.

+

–

150Ω

SW

50F

IF counter buffer seek/stop

switching

During FM reception:

5 V: Seek mode

23

2.5 V: Forced SD mode

0 V: Reception mode

AM reception

SD

23

51kΩ

(two modes: 0 and 5 V)

5 V: Seek mode

0 V: Reception mode

STOP

IF

BUFF.

Forced SEEK

SD: 2.5V 5V

A13568

V

CC

FM

S-meter

24

32

AM/FM signal meter

Fixed-current drive signal meter

output

32

24

10kΩ

AM

S-meter

In AM mode, pin 32 outputs a

1-mA current. Thus the HCC

circuit is turned off.

Dedicated FM signal meter

10kΩ

AM/FM

SW

Outputs a 1-mA

current during AM

reception

AM/FM

SW

MRC

A13569

The voltage V23 switches

between three modes as follows.

FM reception:

5 V: The SD pin operates linked

to the IF counter buffer.

AM/FM

SD

Stereo

indicator

2.5 V: Forced SD mode: operates

as the SD pin.

0.7 V: Reception mode: stereo

indicator

26

Stereo indicator for the SD pin

Seek/stop

switching

26

AM reception: (two modes: 0 and 5 V)

5 V: Operates as the seek SD pin.

0 V: Reception mode. Not used.

100kΩ

V

DD

A13570

Continued on next page.

No. 6655-10/54

LA1787M

Continued from preceding page.

Pin No. Function

Description

Equivalent circuit

V

CC

V

CC

2µA

C2

27

The MRC detector time constant

is determined by a 100 Ω resistor

and C2 when discharging and by

the 2-µA current and C2 when

charging.

100Ω

27

MRC control voltage time

constant

Pin 28

A13571

V

REF

The sub-output is controlled by a

0 to 1-V input.

28

SNC control input

28

A13572

V

REF

The high band frequency output is

controlled by a 0 to 1-V input.

It can also be controlled by the

MRC output.

29

HCC control input

Use a resistor of at least 100 kΩ

when controlling with the pin 32

FM S-meter signal.

32

29

+

1µF

A13573

Continued on next page.

No. 6655-11/54

LA1787M

Continued from preceding page.

Pin No.

Function

Description

Equivalent circuit

V

CC

FM

detector

output

31

Pin 30 is the noise canceller input.

The input impedance is 50 kΩ.

10kΩ

30

31

Noise canceller input

AM/FM detector output

V

CC

Pin 31 is the AM and FM detector

output

In FM mode, this is a low-

impedance output.

In AM mode, the output

impedance is 10 kΩ.

To improve the low band

separation, use a coupling

capacitor of over 10 µF.

1µF

AM

detector

+

30

Noise

canceller

50kΩ

4.2V

A13574

V

CC

32

FM S-meter output block

MRC AC input block

Adjust the external 1-kΩ resistor

to attenuate the MRC AC input

and control the circuit.

10kΩ

+

1µF

1kΩ

32

IF S-meter output and MRC

DC input

MRC input

A13575

C1

+

0.1µF

•The muting time constant is

determined by an external RC

circuit as described below.

Attack time: T_A= 10 kΩ × C1

Release time: T_R= 50 kΩ × C1

33

V

CC

50kΩ

10kΩ

MUTE

AMP.

•Noise convergence adjustment

The noise convergence can be

adjusted when there is no input

signal by inserting a resistor

between pin 33 and ground.

33

Mute drive output

SEEK

OFF

SOFT HOLE

MUTE DET

Band

muting

50kΩ

•Muting off function

Ground pin 33 through a 4-kΩ

resistor.

SD circuit

A13576

Continued on next page.

No. 6655-12/54

LA1787M

Continued from preceding page.

Pin No.

Function

Description

Equivalent circuit

0.1µF

V

R1

REF

V

CC

C

R2

37

36

35

34

V

CC

•The resistor R₁determines the

width of the band muting function.

Increasing the value of R₁

narrows the band.

Quadrature

detector

Reducing the value of R₁widens

the band.

34

35

36

37

AGC

QD output

QD input

V_REF

•Null voltage

When tuned, the voltage between

pins 34 and 37, V

The band muting function turns

, will be 0 V.

HOLE

DET

34 – 37

3pF

on when |V_{34 – 37}| ≥ 0.7 V.

V

₃₇= 4.9 V

1kΩ

IF limitter amplifier

Band

muting

A13577

R

SD ADJ

38

A 130-µA current flows from pin

38 and, in conjunction with the

external resistance R, determines

the comparison voltage.

38

FM SD ADJ

130µA

+

–

SD

Comparator

24

S-meter

A13578

S-meter

24

6.4kΩ

3.6kΩ

The keyed AGC operates when

the voltage created by dividing the

pin 24 S-meter output voltage by

the 6.4 and 3.6 kΩ resistors

becomes lower than the voltage

determined by the resistor

Comparator

KEYED

AGC

+

–

39

Keyed AGC

AM stereo buffer

39

90µA

1.3V

between pin 39 and ground.

V

CC

This pin also is used as the AM

stereo IF buffer pin.

AM IF out

50pF

150Ω

A13579

Continued on next page.

No. 6655-13/54

LA1787M

Continued from preceding page.

Pin No. Function

Description

Equivalent circuit

V

CC

20kΩ

+

20kΩ

The HCC frequency characteristics

are determined by the external

capacitor connected at this pin.

41

HCC capacitor

41

2200pF

A13580

This pin is used to change the

frequency characteristics of the

unneeded audio band under

100 Hz in AM mode to produce

a clear audio signal.

V

CC

C

42

Note: The LC capacitor must be

connected between this pin

and V_CC(pin 40).

V

CC

DET

42

AM L.C. pin

This is because the detector

circuit operates referenced

50kΩ

1kΩ

+

–

to V_CC

.

50kΩ

The cutoff frequency f_Cis

determined by the following

formula.

A13581

f_C= 1/2π × 50 kΩ × C

V

CC

19kHz 0°

BIAS

30kΩ

Inserting a 1-MΩ resistor between

pin 43 and V_CCwill force the IC

to mono mode.

30kΩ

43

Pilot detector

+

43

1µF

+

A13582

Continued on next page.

No. 6655-14/54

LA1787M

Continued from preceding page.

Pin No. Function

Description

Equivalent circuit

V

CC

+

C

0.022µF

2.2µF

240kΩ

42

44

V

CC

G1; Used for time constant

switching during seeks.

• Reception

τ = 2.2 µF × 300 kΩ

• Seek

DET

50kΩ

44

IF AGC

τ = 2.2 µF × 10 Ω

The external capacitors are

connected to V_CC

This is because the IF amplifier

operates referenced to V_CC

.

IF

AGC

G1

.

SEEK

ON

10Ω

A13583

Pin 40 V

CC

45

Pin 40 V

CC

45

IF output

The IF amplifier load

DET

A13584

V

CC

50pF

46

100Ω

AM antenna damping

drive output

Wide band AGC input

I46 = 6 mA (maximum)

This is the antenna damping

current.

20kΩ

46

V

CC

W.AGC AMP.

ANT DAMPING

DRIVER

A13585

Continued on next page.

No. 6655-15/54

LA1787M

Continued from preceding page.

Pin No. Function

Description

Equivalent circuit

30kΩ

R

47

V

CC

Modify the value of the external

resistor to adjust the muting on

level.

140µA

FM muting on level

adjustment

47

–

+

Inverter

Pin 24

MUTE

A13586

V

CC

5.6V

10kΩ

RF AGC rectification capacitor

The low frequency distortion is

determined as follows:

Antenna

damping

+

–

48

+

Increasing C48 and C57 improves

the distortion but makes the

response slower.

3.3µF

48

57

RF AGC bypass

RF AGC

Reducing C48 and C57

aggravates the distortion but

makes the response faster.

For AGC use

57

+

47µF

A13587

2.6V

10kΩ

Due to the high gain of the limiter

amplifer, care must be taken when

choosing the grounding point for

the limiter amplifer input capacitor

to prevent oscillation.

50

51

50

51

IF bypass

FM IF input

330Ω

0.022µF

IF in

A13588

2kΩ

100Ω

52

IF input

The input impedance is 2 kΩ.

52

A13589

Continued on next page.

No. 6655-16/54

LA1787M

Continued from preceding page.

Pin No.

Function

Description

Equivalent circuit

V

CC

IF OUT 53

• Input and output pin or the first

IF amplifier

• Inverting amplifier

300Ω

53

56

IF amplifier output

IF amplifier input

V56 = 2 V

Input impedance: R_IN= 330 Ω

2.75V

V53 = 5.3 V

Output impedance

R_OUT= 330 Ω

IF IN 56

A13590

Pin 40 V

CC

Pin 40 V

CC

54

OSC

The mixer coil connected to the

pin 54 mixer output must be

wired to V_CC(pin 40).

54

49

Mixer output: 130 µA

Mixer input

The pin 49 mixer input

impedance is 330 Ω

49

330Ω

A13591

W-AGC

N-AGC

62 pin

V

CC

Pins 55 and 58 include built-in

DC cut capacitors.

The AGC on level is determined

by the values of the capacitors

C1 and C2.

55

58

W-AGC IN

AM SD ADJ

Pin 55 functions as the SD

sensitivity adjustment pin in

AM mode.

30pF

55

C1

50pF

N-AGC IN

Muting attenuation

adjustment pin

The output current I55 is 50 µA,

and V55 varies depending on the

value of the external resistor.

The SD function operates by

comparing V55 with the S-meter

voltage.

MIX

IN

58

C2

50µA

+

–

MIX

OUT

AM SD

Signal meter

A13592

Continued on next page.

No. 6655-17/54

LA1787M

Continued from preceding page.

Pin No.

Function

Description

Equivalent circuit

1ST.IF

O S C

59

Double balanced mixer

Pins 59 and 60 are the mixer

10.7-MHz output

V

CC

60

59

60

Mixer output

Mixer input

Pins 63 and 64 are the mixer

input.

This is an emitter insertion type

circuit, and the amount of

insertion is determined by the

capacitors C1 and C2.

30Ω

V

CC

63

64

C1

63

64

5pF

C2

Note:The lines for pins 63 and 64

must be kept separated from

the lines for pins 59 and 60.

RF AMP

5pF

620Ω

A13593

510Ω

V

CC

SD

Pin 6 functions both as the FM

front end V_CCand the AM/FM

switching circuit.

+

–

6

AM/FM

switching circuit

+

6

Front end V_CCAM/FM

switching

FM.F.E

AGC

100kΩ

V6 voltage

When 8 V → FM

OPEN → AM

Mode

3.3V

8V

3

GND

A13594

AM 1st

MIX

to RF

Amp.

62

10kΩ

First mixer input

The input impedance is about

10 kΩ.

1st MIX

INPUT

62

2.1V

A13595

10kΩ

20pF

5.6V

to 2nd

MIX

Crystal oscillator circuit

10

AM 2nd OSC

The Kinseki, Ltd. HC-49/U-S and

a C_Lof 20 pF must be used.

33pF

10

X tal

A13596

No. 6655-18/54

LA1787M

Block Diagram

2 2 p F

9 . 1 V

+

5 . 6 V

+

2 2 p F

F µ 0 . 2 2

F µ 1 0

Ω

1 0 k

Ω

2 . 2 k

Ω

1 0 k

F µ 1

F µ 0 . 2 2

F µ 1 0

1 8 p F

Ω

3 0 k

G N D

F µ

0 . 0 2 2

Ω

3 0 k

Ω

1 0 0

5 p F

+

1 0 p F

Ω

3 0 k

F µ 0 . 1

G N D

Ω

2 0 0 k

F µ 0 . 0 1

6 8 0 0 p F ₊

O U T

M P X

1 0 0 0 p F

P I . C A N A D J

F µ 0 . 0 1

D

A N T

5 p F

2 2 p F 2 2 p F

O S C

1 S T

A M

C O U N T E R

G A T E T R I G A G C

R I X D E C

M A T S U B

Ω

1 0 0 k

1 0 0 0 p F

F F

B U F F

Ω 3 0

8 p F

B U F F

S E P . A D J

0 . 0 4 7

I N P U T

P I C A N

A M P

3 8 k < 0

F F

C C

V

A M P

N O I S E

Ω

2 0 k F µ

F µ

A M / F M

0 . 0 2 2

P - C A N

C C

F E V

M I X

C S B 9 1 2 J F 1 0 8

D E T

P I L O T

T R I G

L P F

H P F

F µ 1

F µ 0 . 2 2

C C

Ω 3 0

V

+

A G C

K E Y E D

+

I N P U T

A M P

R F A G C

1 9 k < 0

F F

Ω

5 . 6 k

M U T E A T T

V C O

H C

M A I N

I N D

S D / S T

W . B . A G C

6 2 p F

C O M P

P H A S E

S T O P

V C O

1 9 k < 9 0 k

S W

S E E K

F F

S - M E T E R

A M / F M

V R E F

A M F M

F µ 0 . 4 7

G N D

F E I F I N

H C C

S N C

Ω

2 0 k

W B A G C

R F A G C

+

F M W B A G C I N

A M M I X O U T

S W

A M / F M

I F

R E G

T W E E T

M I X

A M S D A D J

Ω

1 0 k

M R C

F µ 1

I F B U F F

F M I F O U T

C L A M D P E T

A F C D C - C

S N C

L . C .

F µ

0 . 0 2 2

A N T D

F M S D

F M V S M

A M S D

A M V S M I F

A G C

D R I V E

M U T E

D E T

H O L E

Ω

5 1 0 k

D E T

H C C

A M I F I N

1 0 0

F µ 1

Ω

N C - I N

B U F F

F µ

0 . 0 2 2

3 0 M H

a m p l i f i e r

I F l i m i t e r

8 2 0 0 p F

+

2 2 0

A M H C

A M P

M U T E

Q . D E T

+

H µ 1 0 0

A D J

F M I F I N

1 5 p F

D E T O U T

F C 1 8

A M L E V E L

Ω

5 0 k

B U F F

O S C

M E T E R

F M

D

A N T

O S C

Ω

1 0 0 k

H µ 1 0 0

1 M H

0 . 0 2 2

Ω 1 k

Ω 3 0

Ω 1 k

F µ 1

F µ

0 . 0 2 2

F µ

R F A G C

Ω

1 0 k

F µ 0 . 1

Ω

2 4 0 k

+

Ω

1 0 k

+

G N D

F µ

0 . 0 2 2

C C

V

No. 6655-19/54

LA1787M

AC Characteristics Test Circuit

+

Ω

1 0 0 k

Ω

1 0 0 k

Ω

1 0 k

1 M

+

F µ 1

F µ

0 . 0 1 5

R I G H T C H .

L E F T C H .

F µ 0 . 1

A F C I N

F µ 0 . 4 7

N . C . M P X G N D

Q D O U T

Q D I N

+

Ω

1 0 k

R E F

V

Ω

1 0 k

1 M

F M S D A D J .

Ω

2 2 k

Ω

6 . 8 k

K E Y E D A G C

F µ 0 . 2 2

F µ 0 . 4 7

Ω 1 M

F µ 0 . 0 1

1 0 k

+

F µ 1 0 0

Ω

1 0 k

C H C C

2 2 0 0 p F

3 0 0 p F

A M L C

F µ

0 . 0 2 2

P I L O T D E T

F µ 1

F µ

2 5 p F

0 . 0 2 2

2 0 p F

F µ

0 . 0 2 2

F µ 2 . 2

A M / F M

5 p F

I F 7

Ω

1 8 0 k

F E G N D

M U T E O R A D J

Ω 3 0 k

R F A G C

Ω

1 5 k

F µ 1

A N T D

F µ 3 . 3

Ω

3 3 0

2 0 0

C C

F M V

F M G N D

Ω

3 3 0

3 9 p F

Ω

1 0 0 k

Ω

Ω 3 0

Ω

2 0 k

F µ

0 . 0 2 2

Ω 5 0

+

F µ 4 7

Ω 5 0

Ω

1 0 0 k

Ω

2 0 0 k

3 0 k

+

F µ

0 . 0 2 2

6 . 8 m H

+

No. 6655-20/54

LA1787M

Test Conditions

Switch states

Parameter

Symbol

SW1

SW2

b

SW3

SW4

b

a

b

SW5

—

SW6

ON

OFF

ON

OFF

SW7

OFF

—

SW8

OFF

SW9

ON

SW10

—

ON

—

Current drain

I_CCO-FM

ON

OFF

ON

Demodulation output

Pin 31 demodulation output

Channel balance

V_O-FM

b

—

V_O-FM31

CB

ON

b

—

ON

b

—

Total harmonic distortion (FM)

Signal-to-noise ratio: IF

AM suppression ratio: IF

THD-FMmono

S/N-FM IF

AMR IF

ON

b

—

ON

b

—

ON

b

—

Att-1

ON

b

—

Muting attenuation

Att-2

ON

b

—

Att-3

ON

b

—

Separation

ST-ON

ON

b

—

Stereo on level

ON

b

—

Stereo off level

ST-OFF

THD-Main L

PCAN

ON

b

—

Main total harmonic distortion

Pilot cancellation

ON

b

—

ON

b

—

OFF OFF/ON

SNC output attenuation

HCC output attenuation 1

HCC output attenuation 2

Input limiting voltage

Muting sensitivity

AttSNC

ON

b

—

OFF

—

ON

—

AttHCC-1

AttHCC-2

Vi-lim

ON

b

—

ON

b

—

ON

b

—

Vi-mute

ON

b

—

SD sensitivity 1

SD-sen1 FM

SD-sen2 FM

V_IFBUFF-FM

ON

b

OFF

ON

OFF

—

SD sensitivity 2

ON

b

IF counter buffer output

ON

b

V_SMFM-1

ON

b

V_SMFM-2

ON

b

—

Signal meter output (FM)

V

_SMFM-3

_SMFM-4

ON

b

—

V

ON

b

—

Muting bandwidth

Mute drive output

N-AGC on input

W-AGC on input

Conversion gain

Oscillator buffer output

Gate time 1

BW-mute

V_MUTE-100

V_NAGC

ON

b

—

ON

b

—

ON

a

—

V_WAGC

ON

a

ON

—

A.V

ON

a

ON

—

V_OSCBUFFFM

τGATE1

SN

ON

a

ON

—

ON

—

OFF

—

Noise sensitivity

NC effect

ON

—

SN-NC

ON/OFF

ON

—

MRC output

V_MRC

—

MRC operating level

Practical sensitivity

Detection output

Pin 31 detection output

AGC F.O.M.

MRC-ON

S/N-30

ON

—

OFF

ON

OFF

—

V_O-AM

—

V_O-AM31

V_AGC-FOM

S/N-AM

THD-AM

V_SMAM-1

—

Signal-to-noise ratio

Total harmonic distortion (AM)

—

Signal meter output (AM)

Oscillator buffer output

Wide band AGC sensitivity

V_SMAM-2

—

V_{OSCBUFF AM-1}

W-AGCsen 1

W-AGCsen 2

SD-sen1 AM

SD-sen2 AM

V_IFBUFF-AM

—

SD sensitivity

—

IF buffer output

—

No. 6655-21/54

LA1787M

Usage Notes

1. Notes on V and Ground

CC

Pin 40

Pin 25

Pin 14

Pin 61

* Pin 6

Pin 3

V_CCfor the FM IF, AM, NC, MPX, and MRC blocks

Ground for the FM IF and AM blocks

Ground for the NC, MPX, and MRC blocks

V

_CCfor the FM front end, AM first mixer, and first oscillator blocks

_CCfor the FM front end and AGC blocks, and the AM/FM switching pin

Ground for the FM front end, first mixer, and first oscillator blocks

*: When applying the V_CCvoltage to pin 6, that voltage must not exceed the pin 40 and pin 61 V_CCvoltages.

(This condition must be checked carefully when first applying the pin 6 voltage.)

2. Notes on AM Coil Connection

The V used for the first oscillator coil connected to pin 7 must be at the same potential as pin 61.

CC

Connect to the IFT connected with pin 45, and to the MIX coil connected with pin 54. V must be at the same potential

CC

as pin 40.

3. AM/FM Switching

Pin 6 is also used as the FM front end and RF AGC V

CC

Pin 6 voltage

Mode

FM

8

OPEN

AM

Fig. 1

LA1787M Overview

1. Notes on the LA1781M, LA1784M, and LA1787M

The LA1784M is a version of the LA1781M that uses an external oscillator circuit, and has the same characteristics as

the LA1781M.

The LA1787M is a version of the LA1784M that features improved characteristics.

LA1781M

LA1784M

LA1787M

This product is a version of the LA1781M

with the oscillator circuit removed. It

supports the use of an external oscillator

circuit.

The LA1787M features improved

characteristics over the LA1781M

and LA1784M.

It has the same characteristics as the

LA1781M.

No. 6655-22/54

LA1787M

2. Modified circuits

The following characteristics have been improved over those of the The LA1784M.

• The AM adjacent channel interference characteristics (∆40 kHz) have been improved.

• The AM S-meter curve slope has been increased.

• The FM separation temperature characteristics have been improved.

• The stereo indicator sensitivity has been improved.

• The FM oscillator circuit has been omitted.

(1) AM interference characteristics improvement

The second signal interference and suppression have been improved for adjacent channels (±40 kHz) by increasing

the AM second mixer input dynamic range.

(2) The AM S-meter curve slope has been increased.

The slope of the AM S-Meter curve has been increased from that of the LA1781M and LA1784M.

AM S-Meter Voltage

7

6

5

4

3

2

1

0

–20

0

20

40

60

80

100

120

140

Antenna input — dBµ

(3) FM separation temperature characteristics improvement

The temperature characteristics have been improved, the amount of change in the separation due to drift when at

power on has been stabilized. This makes it easier to adjust the separation.

Change in Separation (LA1781M): First IF Input

Change in Separation (LA1787M): First IF Input

60

55

50

45

55

50

45

40

35

40

35

0

1

2

3

0

1

2

3

Time after power on — minutes

No. 6655-23/54

LA1787M

(4) Stereo indicator sensitivity improvement

The stereo indicator sensitivity (on/off) is equivalent to that of the LA1780M

Stereo on level

4.1%

Stereo off level

3.1%

LA1781M/1784M

LA1787M/1780M

2.6%

1.6%

(Typical value)

*: The pilot level such that the stereo indicator goes on or off for a 10.7 MHz unmodulated IF input.

(5) FM oscillator circuit removed

The internal FM oscillator circuit provided in the LA1781M has been removed. The FM oscillator level can be

adjusted by constructing an external circuit block.

*: However, this requires 4 more external parts than the LA1781M: 1 transistor and 3 resistors/capacitors.

IC internal

V

CC

V

CC

4

Vt

A13600

A13601

LA1780M/1781M FM OSC

LA1787M/1784M FM OSC

3. Gain distribution

The table below shows the gain distribution of the LA1780M, LA1784M, and LA1787M. (These are measured

values.) Compared to the LA1784M, the total gain is lower.

1st MIX (10.7)

10 dB

1st IF (10.7)

3.3 dB

2nd MIX (450)

3.2 dB

2nd IF (450)

69 dB

LA1780M

LA1784M

LA1787M

7.5 dB

13 dB

7 dB

66 dB

7.5 dB

3.5 dB

8.6 dB

67 dB

First mixer

: No circuit changes from the LA1784M.

First IF amplifier

Second mixer

: Equivalent to the LA1780M circuit. (The gain is lower than that in the LA1781M and LA1784M.)

: The mixer circuit has been modified to improve adjacent channel suppression and interference.

: Equivalent to the LA1780M circuit.

Second IF amplifier

No. 6655-24/54

LA1787M

4. Changes to applications

Component values that change from LA1781M/LA1784M applications

(Since the total AM gain has changed in the LA1787M)

• AM SD adjustment resistor (pin 55): Because Vsm is higher.

• AM level adjustment resistor (pin 31): Since the post-detection audio amplifier gain is higher than in the LA1781M

and LA1784M, the output level is also higher. This resistor must be changed

to match the set value.

• AM mixer coil (pin 54), IFT coil (pin 45) damp resistor: Since the IF block gain is increased, the mixer (pin 54) and

IFT (pin 45) coil damping must be adjusted.

• Separation adjustment resistor (pin 19): Since an internal 4 kΩ resistor has been added to the pin 19 input circuit to

improve the separation temperature characteristics, the value of the external

resistor must be reduced from that used with the LA1780M, LA1781M, and

LA1784M. (See the following page.)

DECODER

Composite Sign

5kΩ

Added 4 kΩ resistor

19

30kΩ

0.047µF

A13602

A13603

LA1787M

LA1781M/1784M

Functions

1. Notes on the FM Front End

Notes on interference rejection characteristics

• Intermodulation characteristics

The LA1787M applies two high-band AGC functions to prevent IM (the generation of intermodulation). These are

the narrow AGC (pin 58: mixer input detection type) and the wide AGC (for the pin 55 input), and this results in the

antenna frequency characteristics shown in figure 2. The levels at which the AGC functions turn on are determined

by the capacitors attached at pins 55 and 58.

∆f — AGC Sensitivity

When ∆f = 0, 98.1 MHz

110

100

The wide AGC

sensitivity when

90

pin 39 is 5 V.

80

70

The narrow AGC

sensitivity when

pin 39 is at ground.

60

50

–3

–2 –1

0

1

2

3

4

5

–5

–4

∆f

—

MHz

Fig. 2

No. 6655-25/54

LA1787M

• Notes on second-channel attenuation suppression

Keyed AGC (3D AGC) is a technique for achieving good characteristics for both intermodulation and second-

channel attenuation at the same time. When the desired signal is faint or nonexistent, the high-band AGC level will

be essentially 0, and as a result automatic tuning may malfunction and blocking oscillation may occur in the

presence of strong interfering stations. Keyed AGC helps resolve these problems.

This 3D AGC technique uses information that has the following three frequency characteristics and is a unique

Sanyo-developed system for determining the high-band AGC level.

RF and ANT circuit information: Mixer input AGC

Mixer circuit information: Mixer output AGC

CF selectivity information: S-meter output

• 3D AGC Features

Feature

Merit

Only the narrow AGC sensitivity (operation at ∆f < 1.5 MHz) is

controlled by the field strength of the desired station.

• Effective in resolving second-channel attenuation problems.

The narrow AGC sensitivity is controlled by a voltage (V₂₃) that is

under 0.5 V.

• Allows effective resolution of second-channel attenuation problems without

degrading three-signal characteristics.

• Seek operations may stop incorrectly due to the occurrence of

intermodulation.

• It is possible to prevent the occurrence of intermodulation in the RF tuning

circuit and antenna in the presence of strong interfering stations, and

blocking oscillation due to AGC operation can be prevented.

The wide AGC can operate even when V₂₃= 0 (when the desired

station is not present).

The narrow and wide AGC sensitivities can be set independently.

(See figure 3 and 4.)

• Settings can be optimized for the field conditions.

• Since the narrow AGC operates for the desired station and adjacent

stations, the wide AGC sensitivity can be lowered and AGC malfunction

due to local oscillator signal can be prevented.

The system has two AGC systems: narrow and wide AGC.

(See figure 5.)

∆f — AGC on Level (ANT input)Fig.4

∆f — AGC on Level (ANT input)

Fig.3

Pin 55 capacitor: 3 pF

110

100

110

100

90

80

70

60

50

Pin 55 capacitor: 10 pF

Pin 58 capacitor:

10 pF

80

keyed AGC

70

39

Pin 58 capacitor:

47 pF

60

5V

50

–3

–2 –1

0

1

2

3

4

5

–3

–2 –1

0

1

2

3

4

5

–5

–4

–5

–4

∆f

—

MHz

∆f

—

MHz

W-AGC, N-AGC — f

Fig.5

70

80

90

100

110

120

AGC input level frequency

characteristics such that

130

140

V_RFAGC (pin 2) falls under 2 V.

7

2

3

5

7

2

3

5

7

100

2

3

5

1.0

10

Frequency, f — MHz

No. 6655-26/54

LA1787M

3D AGC Sensitivity Characteristics

AGC sensitivity

Wide AGC sensitivity

∆F

1

2

Second-channel

attenuation improvement

Narrow AGC sensitivity

3

Desired station AGC sensitivity

4

V

(Desired station field strength)

23

A12075

Fig. 6

3D AGC Sensitivity — ∆f, V characteristics

23

• The wide AGC sensitivity is determined by the antenna and RF circuit selectivity, regardless of V .

23

• The narrow AGC sensitivity is determined by the following.

The total selectivity of the antenna, RF circuit, and mixer when V ≥ 0.5 V

23

The above selectivity and V when V < 0.5 V

23

• The improvement in the second-channel attenuation corresponds to the area occupied by the narrow AGC in the

total AGC sensitivity area.

Figure 8 on the next page shows the actual operation of the circuit.

∆f — AGC on Level (ANT input)

110

f

= 98.1 MHz

Second-channel pad

D

100

90

80

70

60

50

ANT IN

V

IN

fu = 98.1 MHz + ∆f

A12076

–3

–2 –1

0

1

2

3

4

5

–5

–4

∆f

—

MHz

Fig. 7

No. 6655-27/54

LA1787M

Notes on 3D AGC (Keyed AGC)

V

CC

W-AGC

DET

55

N-AGC

DET

58

S-meter

90µA

+

–

V

CC

+

–

1

2

+

39

24

ANT

DUMPING

VS-meter

A11763

Fig. 8

• The antenna damping current from the pin due to the pin diode flows when the V2 pin reaches the V - V

CC

BE

level.

• The narrow AGC operates as follows.

When pin V39 > pin V24: The narrow AGC turns off.

When pin V39 < pin V24: The narrow AGC turns on.

No. 6655-28/54

LA1787M

• The LA1787M includes two AGC circuits in its front end block.

— Antenna input limiter using a pin diode.

— FET second gate control

The AGC input pin is pin 59, and the AGC circuit turns on when a signal of about 30 mVrms is input.

AGC activation

The pin diode drive circuit turns on when V – V2 is greater than or equal to about 1 V, and input limitation is

CC

applied to the antenna circuit. In application circuits, there will be an attenuation of about 30 to 40 dB. Next, when

an adequate current flows in the antenna attenuator pin diode, the inductance falls, the FET second gate voltage

drops, the FET gm falls, and the AGC operates. The recommended FET is the Sanyo 3SK263, which is an

enhancement-type MOSFET. Therefore, full AGC is applied when the voltage, V , between the second gate and

G2-S

the source is 0. Note that if a depletion-type MOSFET is used, AGC will not be applied unless V

is less than 0.

G2-S

V2 AGC Characteristics

Fig.9

9

8

7

6

5

4

3

2

1

fr = 98.0 Hz

V

= 8 V

CC

Ta = 25°C

Range where AGC level AGC level due

the AGC does due to the

to the MOSFET

second gate:

about 35 dB

not operate

pin diode:

about 35 dB

0

–10

0

10 20 30 40 50 60 70 80 90 100 110 120 130 140

ANT IN

— dBµ

• Mixer

The mixer circuit in this IC is a double-balanced mixer with both

balanced input and balanced output.

Input circuit type

64

59

60

63 62

Emitter input

Input impedance: 25 Ω

Due to optimized device geometry, emitter current, the bias, this IC

achieves the following performance.

MIX

Mixer input usable sensitivity: 15 dBµ

Mixer input IMQS: 90.5 dBµ

(For an oscillator level of 200 mVrms)

OSC

* The mixer input IMQS is defined as:

fr = 98.8 MHz, no input

fu1 = 98.8 MHz, 1 kHz, 30% modulation

fu2 = 99.6 MHz, no modulation

The interference 1 and 2

input levels such that

generated intermodulation

output signal-to-noise ratio

becomes 30 dB when an

interference signal with the

same level as the mixer input

is input, and distortion occurs

in the mixer.

Mixer circuit

Fig. 10

A12077

No. 6655-29/54

LA1787M

• Oscillator

Figure 11 shows the type of oscillator circuit used in this IC. It includes both an oscillator and an oscillator buffer.

V

CC

18pF

4

25pF

20pF

AM/FM

OSC BUFFER OUT

5

VT

A12078

Fig. 11

• Figure 12 shows the type of FM first IF amplifier used in this IC. It is a differential single-stage amplifier.

330Ω

TO MIX

FM IF input

56

53

330Ω

+

–

330Ω

A12079

Fig. 12

Specifications

Input impedance: 330 Ω

Output impedance: 330 Ω

Gain: 20 dB

No. 6655-30/54

LA1787M

2. FM IF

• Notes on the FM SD and SD adjustment

The figure below presents an overview of the FM SD and the IF count buffer.

+

–

R

4.9V

+

–

R

Band

muting

Muting

drive

output

HOLE

CLET

STEREO

IND

S-meter

IF count buffer

+

–

FM IF

39

24

33

23

26

5V

IF count output

SD

STEREO/MONO

2.5V 5V

Fig. 13

A11759

Figure 14 shows the relationship between the FM SD, the IF count buffer output, the S-meter, and the muting drive

output.

Larger

S-meter

V

values

of R

24

38

33

Smaller values of R

33

V

33

over 0.7 V

33

over 0.7 V

V

26

5 V

On as an

SD signal

SD

ON

SD

ON

Mono

0.7 V

Stereo

V

23AC

IF count

buffer

OFF

IF counter output off

2.5 V

V

23DC

5 V

0 V

RDS and other types of SD detection can be used by switching these modes.

New LA1784M functionality:

For stereo input (when the V26 pin voltage is 0.7 V),

when this pin is shorted to ground (0.1 V or lower)

the IC will operate in forced mono mode.

A11758

Fig. 14

No. 6655-31/54

LA1787M

• Transient response characteristics during automatic tuning

The transient characteristics for SD and IF count buffer on/off operation are determined by the time constants of

the RC circuits attached to the following pins.

(1) Muting time constant: pin 33

(2) S-meter time constant: pin 24

(3) AFC time constant: pin 34

There are two points that require consideration when using fast tuning.

(1) The SD time constant due to the S-meter time constant

Since the current I24 (pin 24) varies with the field strength, the time constant also changes. There is no hysteresis

in the comparator.

If a smaller value is used for C24, you must select a value for C such that the AGC does not become unstable

when the pin 24 voltage is used for keyed AGC.

S-meter

10k

24

C

24

A12080

Fig. 15

(2) The SD time constant due to the pin 33 muting voltage time constant

The changes in volume due to field fluctuation during weak field reception can be made smoother by setting the

attack and release times during soft muting operation.

Mute

drive

Mute

amp

Muting time constants

Attack: 10 kΩ × C33

Release: 50 kΩ × C33

10kΩ

50kΩ

Attack

Release

33

C

33

A11766

Fig. 16

SD Sensitivity Adjustment

Fig.17

50

40

30

20

10

0

6

10

14

18

22

26

30

34

Resistance between the pin and ground — kΩ

No. 6655-32/54

LA1787M

However, when testing this stop sensitivity, note that when checking the waveform on the IF count buffer output

(pin 23), there are cases, such as that shown below, where current in the test system may be seen as flowing to

ground and cause oscillation that causes the IF count buffer output to go to the output state.

IF buffer

amp

F.E.

IF

0.022 µF

5 V

Test system capacitance

The 10.7 MHz feeds back through ground.

A12081

Fig. 18

• FM Muting control pin (pin 47) (R47: 30 kΩ variable resistor)

The –3 dB limiting sensitivity can be adjusted with R47.

FM Soft Muting (1)

Fig.19

R47 = 7.5 kΩ

DET out

15 kΩ

20 kΩ

10 kΩ

Antenna input — dBµ

• FM muting attenuation adjustment (pin 58)

The muting attenuation can be switched between the three levels of –20, –30, and –40 dB by the resistor inserted

between pin 58 and ground. (Note that the exact values depend on the total tuner gain.)

The noise convergence with no input is determined by the pin 58 voltage.

58

R58

Open

Mute ATT

–20 dB

–30 dB

–40 dB

200 kΩ

30 kΩ

100Ω

R

58

A11764

The attenuation can be set by making R33 smaller as listed

in the table above.

33

R

33

A11765

Fig. 20

No. 6655-33/54

LA1787M

FM Soft Muting (2)

Fig.21

FM Soft Muting (3)

Fig.22

R47 = 7.5 kΩ

DET out

10 kΩ

15 kΩ

20 kΩ

15 kΩ

200 kΩ

30 kΩ

2 0kΩ

Antenna input — dBµ

V

CC

Mute amp.

(VCA)

Quadrature detector

200 kΩ

R

+

–

+

–

N-AGC

Mute

drive

Limiter

R

58

33

31

DET out

To MIX out

Open

200 kΩ

30 kΩ

A11767

Fig. 23

• FM muting off function

Forcing this pin to the ground level turns muting off.

Detector

output

0

1

When the pin is at the ground level, the noise convergence will

be 10 dB and the –3 dB limiting sensitivity will be about 0 dBµ.

20

Antenna input

A12082

Fig. 24

No. 6655-34/54

LA1787M

• Hall detection

The Hall detection function detects the level of the pin 36 quadrature input signal and then applies peak detection

to that result. The result is output from pin 33. This circuit has three effects.

(1) It assures that muting will be applied for weak inputs with an antenna input of under 5 dBµ. The amount of

attenuation is referenced to an antenna input of 60 dBµ, fm = 1 kHz, and a 22.5 kHz dev output, and is variable

from 10 dB to 40 dB when there is no input. Thus one feature of this circuit is that the weak input noise

attenuation and the –3 dB limiting sensitivity for over 5 dBµ inputs can be set independently.

Hall Detection Output — Antenna Input Characteristics Fig.25

5

4

3

Area muted by Hall detection

2

1

0

–20

–10

0

10

20

30

Antenna input

— dBµ

(2) When the pin 36 quadrature input is a saturated input, the pin 36 noise level (Va) is detected and a peak-hold

function is applied to pin 33 (Vb) for locations rapid field strength variations and severe multipath occurs for

fields that result in an antenna input level of over 5 dBµ.

36

33

Vb

+

Va

0.1µF

0

A12083

Fig. 26

(3) Unique features

One unique feature of the LA1784M is that if there are adjacent stations such that f = 98.1 MHz and f =

1

2

97.9 MHz, a search operation will not stop at 98.0 MHz. Since V

= 0 V and V = 3.6 V at 98.0 MHz in

SM

AFC

the situations shown in figure 27 and 28, even though Hall detection would normally not operate and SD would

be high, in this IC the Hall detection circuit will operate, V

will be set to 1.2 V (over 0.7 V) and the SD

Mute

signal will go low, thus preventing incorrect stopping of the search.

No. 6655-35/54

LA1787M

Unique Features of the LA1784M Hall Detection Circuit (1) Fig.27

Unique Features of the LA1784M Hall Detection Circuit (2) Fig.28

2

1

²When the tuner is moved in 50 kHz steps.

With a 51 kΩ resistor between pins 37 and 34.

₁With the SD sensitivity adjusted to be 20 dBµ.

When the tuner is moved in 50 kHz steps.

With a 51 kΩ resistor between pins 37 and 34.

With the SD sensitivity adjusted to be 20 dBµ.

f

1

ANT

IN

f

2

0

–1

6

–1

6

4

2

0

6

4

2

4

2

0

6

4

2

0

8

6

4

f

= 97.9 MHz, 120 dBµ

0

8

6

4

2

f

= 97.9 MHz, 40 dBµ

2

fm = 400 Hz, 22.5 kHz dev.

f

= 98.1 MHz, 120 dBµ

1

f

= 98.1 MHz, 40 dBµ

1

fm = 1 kHz, 22. 5kHz dev.

fm = 1 kHz, 22.5 kHz dev.

2

0

97.7

97.8

97.9

98.0

98.1

98.2

98.3

97.7

97.8

97.9

98.0

98.1

98.2

98.3

Frequency, fr — MHz

• Notes on the quadrature input level

When a strong field is being received the quadrature signal input (pin 36) requires a 200 mV rms input, and the

detection transformer and the damping resistor between pins 36 and 37 must be designed.

(We recommend the Sumida SA-208 transformer and a 10 kΩ resistor between pins 36 and 37.)

When the pin 36 input level falls below 160 mV rms, the Hall detection circuit operates and the pin 33 mute drive

output voltage increases. Therefore, when pin 36 input is from 160 to under 200 mV rms during strong field

reception, the muting circuit may or may not operate due to sample-to-sample variations between individual ICs.

Furthermore, the SD function may not operate, and the audio output level may be reduced. Incorrect operation due

to sample-to-sample variations and temperature characteristics can be prevented by keeping the pin 36 voltage at

200 mVrms or higher.

SA208 + LA1787M IF Input Characteristics Fig.30

Pin 33 VMute — QD Input Level Fig.29

6

5

4

3

2

4 0.8

With pins 34 and 37 shorted.

With 5 V applied to pin 24.

3 0.6

2 0.4

1 0.2

THD 1 kHz

75 kHz dev

–100 –80 –60 –40 –20

–120

0

20 40 60 80 100 120

∆f

—

kHz

With the resistor between

pins 36 and 37 open.

–0.2

–0.4

∆f=0→

75 Ω

0.022 µF

75 Ω

+

10.7 MHz

With a 10 kΩ resistor

SG

between pins 36 and 37.

1

0

–0.6

–0.8

Voltage between pins 37 and 34

(referenced to the pin 37 voltage)

36

37

10.7 MHz

96

94

LA1888M

100 102

92

98

104

106

QD input level — dBµ

No. 6655-36/54

LA1787M

Detector output Pin 36 AC level

MPX OUT

R_36-37

Open

10 kΩ

Vo

QDIN

330 mVrms

280 mVrms

235 mVrms

200 mVrms

• Band Muting Adjustment Procedure

The muting bandwidth can be modified as shown in figure 31 with the resistor R

between pin 34 and 37.

BW

R

BW

— Muting Bandwidth

Fig.31

280

240

200

160

120

80

R

BW

+

1 µF

0.47 µF

SA208

Sumida

34

10 kΩ

37 36

35

ANT IN 98 MHz 100 dBµ

40

0

2

3

5

7

2

3

5

7

100

2

1.0

10

Resistor R

between pins 34 and 37 — kΩ

BW

3. AM

• AM AGC system

The LA1787M RF AGC circuit takes its input from three sources: the WIDE AGC pin (pin 46), the MIDDLE

AGC pin (pin 49) and NARROW AGC. There is also an IF AGC circuit.

R

W

1st MIX 10.7MHz CF

2nd MIX 450kHz CF

IF Amp.

DET

62

49

52

31

RF

V

CC

42

44

1st OSC

X'tal

240 kΩ

2.2 µF

V

Amp.

IF AGC

46

Middle AGC IN

Narrow AGC IN

Wide AGC IN

ANT

damping

RF AGC

57

48

Fig. 32

+

47 µF

3.3 µF

A11762

No. 6655-37/54

LA1787M

AM AGC f characteristics Fig.33

100

Wide AGC

Operates for wide

band interference

Wide AGC

Operates for

wide band

90

interference

Middle AGC

Operates for

80

interference within

±70 kHz of the

received frequency.

interference within

±70 kHz of the

received frequency.

₇₀Narrow AGC

Operates at the

received frequency.

60

1000

900

1100

1200

800

Frequency — Hz

Wide Band AGC Circuit

Fig.34

120

Received frequency:

1 MHz

30 Ω

0.022 µF

46

110

100

90

50 Ω

–6dB

0.022 µF

SG

ANTD

510 Ω

0.022 µF

80

70

1.0

2

3

5

7

10

2

3

5

Pin 46 input — MHz

The wide band AGC circuit in this IC has the frequency characteristics shown above. The pin 46 input frequency

characteristics are identical to those of the RF amplifier gate. This AGC circuit serves to prevent distortion at the

FET input when a strong signal is applied to the antenna circuit. The level at which the AGC circuit turns on can be

adjusted to an arbitrary level with the wide band AGC adjustment resistor. A delayed AGC on level can be handled

by reducing the value of the adjustment resistor.

Wide band AGC adjustment resistor

30 Ω

0.022 µF

V

CC

620 Ω

1MH

100 µH

FC18

57

62

100 µH

+

Fig. 35

A12084

No. 6655-38/54

LA1787M

• Notes on AM SD (pin 26) and the SD adjustment pin

SD and the IF buffer are operated by comparing the S-meter level (V24) and the 5 V reference voltage as shown in

figure 36.

S-meter

AM IF

Comparator

V

CC

+

–

IF buff amp.

50 pF

50 µA

55

100 kΩ

24

23

26

100 kΩ

0.47 µF

0.022 µF

IF buffer

5 V

51 kΩ

5 V

SD

Seek

Fig. 36

A12085

Figure 37 shows the relationship between the AM SD, the IF count buffer, and the S-meter.

Larger

values

S-meter

V

24PIN

of R

55

V

55

26

Smaller values of R

55

SD on

V

23AC

23DC

IF buffer on

5 V

OFF

V

Pin 55: AM SD adjustment pin

0 V

A11760

Fig. 37

No. 6655-39/54

LA1787M

• AM high band cut and detector output level adjustment methods

The pin 31 AM and FM tuner output has an impedance of 10 kΩ in AM mode and a few tens of Ohms in FM

mode. Therefore, R31 is used to lower the AM detector output level and C31 determines the AM high band

frequency characteristics.

V

CC

FM

detector

31

R31

C31

V

CC

+

AM

detector

10 kΩ

30

Noise

canceler

input

50 kΩ

A12086

Fig. 39

• AM stereo system pins

To the AM stereo decoder

V

CC

GND

400 mV rms

450 kHz output

IFT

45

39

V

CC

50 pF

150 Ω

Keyed AGC

IF AMP.

Fig. 40

A11761

No. 6655-40/54

LA1787M

• AM low band cut adjustment method

The AM low band frequency characteristics can be adjusted with C42, which is inserted between pin 42 and V

.

CC

Since the detector is designed with V as the reference, C42 must be connected to V

.

CC

Detector Output — Frequency Fig.42

0.022 µF (41pin)

10

0

V

CC

With no used (31pin)

C42

42

0.022 µF (41pin)

With no used (31pin)

–10

–20

–30

–40

50 kΩ

10 kΩ

+

–

10 kΩ

To pin 31

AM

detector

0.043 µF (41pin)

% with no used (31pin)

0.022 µF (41pin)

8200 pF (31pin)

10 kΩ

A12087

Fig. 41

fr = 1000 kHz

fm = 1 kHz, 30%

2

3

5

7

2

3

5

7

2

3

5

7

2

3

5 7

10

0.001

0.01

0.1

1.0

Frequency — Hz

4. Noise Canceler Block

• The noise canceler input (pin 30) has an input impedance of about 50 kΩ. Check the low band frequency

characteristics carefully when determining the value of the coupling capacitor used. Note that f will be about 3 Hz

C

when a 1 µF capacitor is used in the application.

• Pins 8 and 9 are used to set the noise detector sensitivity and the noise AGC. It is advisable to first set the noise

sensitivity for a medium field (an antenna input of about 50 dBµ) with pin 8 (the noise sensitivity setting pin), and

then set the AGC level for a weak field (20 to 30 dBµ) with pin 9 (the AGC adjustment pin). If the noise sensitivity

is increased, the AGC will become more effective but, inversely, the weak field sensitivity will be reduced.

Noise canceler 10 kHz overmodulation malfunction may be a problem. In particular, when an overmodulated

signal is input, the noise canceler may, in rare cases, malfunction. This is due to the fact that the IF detector output

has a waveform of the type shown in figure 43 due to the bands of the IF ceramic filters as shown below. (Here, the

antenna input is 60 dBµ, the ceramic filters are 150 kHz × 1 and 180 kHz × 2, f = 10 kHz, 180 kHz dev.) The noise

canceler reacts to the spikes (whiskers) generated due to this overmodulation, which results in distortion to the

audio output. (The spike components due to overmodulation occur due to the bands of the ceramic filters in the

tuner.) The following describes a method for resolving this problem. This incorrect operation due to

overmodulation is prevented by removing the spike components due to this overmodulation with a low-pass filter

consisting of a 1 kΩ resistor and a 2200 pF capacitor shown in figure 44. However, note that the FM separation

characteristics in the high band and the AM frequency characteristics will change.

H1 W1

2.5OU

IF audio output

f = 10 kHz,180 kHz dev

IF output

31

Noise canceler input

1 kΩ

–

30

1 µF

2200 pF

A12089

Fig. 44

–2.5OU

–19.00 µs

981.00 µs

Fig. 43

A12088

No. 6655-41/54

LA1787M

5. Multiplexer Block

• HCC (high cut control) frequency characteristics (pin 41)

When the HCC function operates, the frequency characteristics of the output signal are determined by the

capacitance of the external capacitor connected to pin 41.

20 kΩ

To the

VO

matrix

(dB)

41

C

A12090

Fig. 45

f

1

(Hz)

2πC × 20 kΩ

1

f = ——————— [Hz]

A12091

C

Fig. 46

2π × C × 20 kΩ

Frequency Characteristics Fig.47

Changes in the pin 41 capacitor capacitance (for a 100% high cut ratio)

0.001 µF

10

0

–10

–20

–30

–40

0.0022 µF

0.0047 µF

V

= 8.0 V

CC

–50

–60

f = 98 MHz 100%mod

80 dBµ IN

3

5

7

2

3

5

7

2

3

5

7

10k

2

3

100

1k

Frequency, f — Hz

• Pilot canceler adjustment (pins 17 and 18)

Noise

30

–

To the

multiplexer

canceler

input

Fig. 48

Gate

Pilot

cancel

11

12 17

18

6800 pF 3.9 kΩ 0.01 µF 50 kΩ

A12092

The pilot canceler signal waveform (pin 19) is a 19 kHz signal that contains no third harmonic as shown in figure

48. Since this signal has the same phase as the pilot signal, no capacitor is required between pin 18 and ground.

Since it has no third harmonic component, excellent pilot cancellation can be acquired in both the left and right

channels by adjusting with a variable resistor.

No. 6655-42/54

LA1787M

• Separation adjustment (pin 19)

5 kΩ

To the

Larger

subdecoder

19

20 kΩ

0.047 µF

A12094

C

Fig. 49

A12093

The separation is adjusted by modifying the input level to the subdecoder with the variable resistor connected to

pin 19. Since only the sub-modulation level is changed by changing the variable resistor setting, the monaural

(main) output level is not changed. Furthermore, degradation of high band separation in the decoder can be avoided

if the impedance of the external capacitor (C) in the subchannel frequency band (23 to 53 kHz) is made sufficiently

smaller than the variable resistor.

6. MRC Circuit

V

CC

2 µA

100 Ω

FM

S-meter

DC buffer

MRC

QMRC

30 kΩ

6.4 kΩ

10 kΩ

75 pF

3.6 kΩ

1 kΩ

24

32

27

Noise amplifier

High-pass filter with

Fc = 70 kHz + amplifier

+

C27

V

CC

An external transistor equivalent

to the 2SC536 is required

To the SNC, pin 28

Reason: A QMRC level shifter is

required to allow a simplified MRC

circuit to be used in the LA1787M.

A11768

Fig. 50

No. 6655-43/54

LA1787M

(1) When there is no AC noise on pin 32

V

24

= V –V

27

BE

↑

Q

MRC

V27 is about 2.5 V when the antenna input is 60 dB or higher.

(2) Since the MRC noise amplifier gain is fixed, the MRC circuit is adjusted by reducing the AC input level.

32

+

Fig. 51

A11769

(3) The MRC attack and release are determined by C27 on pin 27.

Attack: 7 µA · C27 → 2 µA · C27

Release: 500 Ω · C27 → 100 Ω

Notes on the Noise Canceler

The noise canceler characteristics have been improved by implementing the circuit that determines the gate time in

logic. Since the time constant in earlier noise cancelers was determined by an RC circuit such as that shown in figure

52, the rise time shown in figure 53 was influenced by the values of the resistor and capacitor used. As a result the

noise exclusion efficiency was reduced by this delay in the rise time. In the LA1787M, this rise time was shortened by

implementing the circuit that determines the gate time in logic, allowing it to reliably exclude noise.

A11772

A11771

Fig. 53

Fig. 52

No. 6655-44/54

LA1787M

Gain Distribution (FM)

This section investigates the gain in each block in the LA1787M when the Sanyo recommended circuits are used.

(Test conditions)

Ambient temperature: 26°C

Antenna and mixer input frequency: 98.1 MHz

First and second IF input frequency: 10.7 MHz

The input levels when V = 2 V will be as follows.

SM

ANT IN: 19 dBµ

MIX IN: 30 dBµ

1st IF IN: 42 dBµ

2nd IF IN: 60 dBµ

When the gains for each block are determined according to the above, the results are as follows.

RF GAIN: 11 dB

MIX GAIN: 12 dB

1st IF GAIN: 18 dB

1st IF IN 56 pin

FM

MIX IN 64 pin

RF

ANT IN

2nd IF IN 51 pin

11 dB

12 dB

18 dB

A11773

Fig. 54

No. 6655-45/54

LA1787M

(AM)

This section investigates the gain in each block in the LA1787M when the Sanyo recommended circuits are used.

(Test conditions)

Ambient temperature: 26°C

Antenna and mixer input frequency: 1 MHz

First and second mixer input frequency: 10.7 MHz

Second IF input frequency: 450 kHz

The gains at each stage will be as follows.

RF Gain (ANT IN-pin62): 17 dB

1st MIX Gain (pin62-pin56): 8 dB

1st IF Gain (pin55-pin53): 15 dB

AM

1st MIX

1st IF

2nd MIX

2nd IF

AM DET

RF

Gain

1st MIX

Gain

1st IF

Gain

2nd MIX

Gain

2nd IF

Gain

A11774

Fig. 55

No. 6655-46/54

LA1787M

Input Circuits for Each Stage

[FM]

• Mixer input

• First IF input

0.022 µF

75 Ω

0.022 µF

300 Ω

75 Ω

63

64

56

75 Ω

V

IN

fr = 10.7 MHz

Actual

A11776

measurement

A11775

• IF input

0.022 µF

75 Ω

300 Ω

51

50

75 Ω

330 Ω

0.022 µF

fr = 10.7 MHz

A11777

[AM]

• First mixer input

• Second mixer input

0.022 µF

50 Ω

0.022 µF

50 Ω

62

49

50 Ω

fr = RF

fr = 10.71 MHz (f2nd osc + 0.45 MHz)

A11778

A11779

IFT

• IF input

• Del input

0.022 µF

50 Ω

0.022 µF

50 Ω

52

45

fr = 450 kHz

A11780

A11781

No. 6655-47/54

LA1787M

Sample AM tuner Circuit with the LC72144 Used Together

2nd MIX

IF

CF

RF

450K

1st IF

300 Ω

XBUFF

fosc

LC72144

A11782

AM 1st IF

10.7 MHz

10.8 MHz

Step

FM IF

1

2

f

_OSC10.25 MHz

_OSC10.35 MHz

10 kHz, 11 kHz

9 kHz, 10 kHz

10.7 MHz

10.8 MHz

f

1st MIX

IF

10.71 MHz

10 kΩ

CF

RF

AF

62

59

60

56

53

49

54

52

1st OSC

2nd OSC

Lch

31

NC

MPX

Rch

10.26 MHz

IF

10.7 MHz

AF

CF

Quadrature

detector

RF

63

64

60

59

56

53

51

A11783

No. 6655-48/54

LA1787M

Crystal Oscillator Element

Kinseki, Ltd.

Frequency: 10.26 MHz

CL: 20 pF

Model No.: HC-49/U-S

Coil Specifications

Sumida Electronics, Ltd.

[AM Block]

AM FILTEER (SA-1051)

AM OSC (SA-359)

S

3

2

1

4

1

2

3

6

4

AM IF1 (SA-264)

AM IF2 (SA-1063)

3

4

3

2

4

2

S

1

6

1

6

S

AM loading (SA-1062)

AM ANT IN (SA-1048)

3

4

3

4

2

1

6

1

6

S

AM RF amplifier (RC875-222J)

0.1ø2UEW

[FM Block]

FM RF (SA-1060)

FM ANT (SA-1061)

S

3

2

1

4

3

2

1

4

6

S

FM OSC (SA-1052)

FM MIX (SA-266)

S

3

2

1

4

C1

8

3

2

1

4

7

C2

6

S

FM DET (SA-208)

A136

S

3

S

4

2

1

6

No. 6655-49/54

LA1787M

The Toko Electric Corporation

[AM Block]

AM FILTEER (A2861BIS-15327)

AM OSC (V666SNS-214BY)

1

2

3

2

1

4

6

4

6

0.1ø2UEW

AM IF1 (7PSGTC-5001A)

AM IF2 (7PSGTC-5002Y)

3

2

1

4

3

2

1

4

6

0.05ø3UEW

AM loading (269ANS-0720Z)

AM ANT IN (385BNS-027Z)

S

3

2

1

4

3

2

1

4

6

0.05ø3UEW

6

S

AM RF amplifier (187LY-222)

0.1ø2UEW

[FM Block]

FM RF (V666SNS-208AQ)

FM ANT (V666SNS-209BS)

3

2

1

4

S

3

2

1

4

ø0.1–2UEW

S

ø0.1–2UEW

S

6

FM OSC (V666SNS-205APZ)

FM MIX (371DH-1108FYH)

3

2

1

4

5

6

3

2

1

4

S

ø0.07–2UEW

S

ø0.12–2UEW

S

6

FM DET (DM600DEAS-8407GLF)

3

2

1

4

6

0.07ø2MUEW

No. 6655-50/54

LA1787M

Coil Specifications

Sagami Elec Co., Ltd.

[AM Block]

AM FILTEER (000021055)

AM OSC (000021056)

S

1

2

3

2

1

4

5.1µH

6

4

6

AM IF1 (000021057)

AM IF2 (000021059)

3

2

4

3

2

1

4

180pF

1

6

S

AM loading (000021061)

AM ANT IN (000021062)

3

4

3

2

4

100µH

30mH

2

1

6

1

6

S

AM RF amplifier (000021063)

2.2mH

[FM Block]

FM RF (000021064)

FM ANT (000021065)

S

3

2

1

4

3

2

1

4

105.5nH

6

S

FM OSC (000021066)

FM MIX (000021067)

S

3

2

1

4

3

2

1

4

5

1-2 : 100pF

2-3 : 100pF

62.7nH

6

S

FM DET (010021075)

3

2

1

4

S

1-3 : 20µH

3-4 : 120pF

6

No. 6655-51/54

LA1787M

Antenna input — dBµ

Input — dBµ

Antenna input — dBµ

Input — dBµ

First IF input — dBµ

Mixer input — dBµ

No. 6655-52/54

LA1787M

Frequency, — MHz

Ambient temperature, Ta — °C

AM I/O Characteristics

20

V

= 8.5 V

CC

f = 1 MHz

mod = 1 k 30%

OUT

0

–20

–40

–60

NOISE

–80

–100

–20

0

20

40

60

80

100

120

140

Ambient temperature, Ta — °C

ANT input, IN — dBµ

AM Distortion

AM DC Characteristics

7.0

6.0

5.0

4.0

3.0

2.0

7.0

6.0

5.0

4.0

3.0

2.0

V

= 8.5 V

V

= 8.5 V

CC

RF AGC

CC

f = 1 MHz

mod = 1 k 30% 80%

1.0

0

1.0

0

–20

0

20

40

60

80

100

120

140

–20

0

20

40

60

80

100

120

140

ANT input, IN

— dBµ

ANT input, IN

— dBµ

No. 6655-53/54


型号：	LA1787M-MPB-E
厂家：	ONSEMI
描述：	单芯片调谐器，用于汽车无线电无线
文件：	总54页 (文件大小：655K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LA1787M-MPB-E [ONSEMI]

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