LA1235 datasheet(4/12 Pages) SANYO

4 / 12 page

LA1235

No.873-4/12

• Setting of muting sensitivity, hysteresis width (Refer to the

equivalent circuit block diagram and application circuit).

Muting sensitivity and hysteresis width are set arbitarily by

varying resistors R204 and R205 connected to pins 15 and 16,

respectively. Muting sensitivity is set by varying R204 ; and

if R204 is made larger, muting sensitivity will shift to the

weak signal side. Hysteresis width is set by varying R205 ;

and if R205 is made larger, hysteresis width will narrow.

Next, how to set muting sensitivity is concretely described as

follows. In case of using R204=50kΩ (semifixed resistor)

and R205=56kΩ, the upper limit of current I16, 50µ A,

delivered from the signal meter driver at which muting is

turned ON is obtained from the first quadrant of Table for

muting adjustable lower limit calculation. Muting is turned

ON at I16≤50µA. If I16≤50µA, muting is already turned ON

at a point of input being stronger than the setting input and it

is impossible to adjust muting at the setting input. Therefore,

I16>50µA is required at the setting input. The input at which

a sample with a small I16 output meets 50µA is obtained as

VIN=47dBµ. This input is the maximum value of muting

sensitivity, that is to say, the lower limit at with muting can

be set. The data for sample with a Small I16 shown in this

Table is colose to the minimum value, but since samples

with values less than this munimum value may occur, a

margin of some dBµ must be allowed. From the above, the

minimum value for muting setting (muting ON input)

becomes 50dBµ for R204 (semifixed resistor)=50kΩ and

R205=56kΩ.

LA1235 Datasheet(PDF) 4 Page - Sanyo Semicon Device