LA1780 データシートの表示（PDF） - SANYO -> Panasonic

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LA1780

Single-Chip Tuner IC for Car Radios

SANYO -> Panasonic 

Continued from preceding page.

Pin No.

Function

LA1780M

Description

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.

IF counter buffer seek/stop

During FM reception:

23

switching

5 V: Seek mode

2.5 V: Forced SD mode

0 V: Reception mode

SD circuit

AM reception

(two modes: 0 and 5 V)

5 V: Seek mode

0 V: Reception mode

Equivalent circuit

IF counter

buffer

Forced

SD: 2.5 V

24

AM/FM signal meter

Fixed-current drive signal meter

output

In AM mode, pin 32 outputs a

32

Dedicated FM signal meter

1-mA current. Thus the HCC

circuit is turned off.

FM

S-meter

AM

S-meter

Outputs a 1-mA

current during AM

reception

FM reception: the voltage V23

switches between three modes

as follows.

5 V: The SD pin operates linked

to the IF counter buffer.

2.5 V: Forced SD mode: operates

26

Stereo indicator for the SD pin

as the SD pin.

0 V: Reception mode: stereo

indicator

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

5 V: Operates as the seek SD pin.

0 V: Reception mode. Not used.

Stereo

indicator

Seek/stop

switching

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