HA12237F

Rev.1.00 Jun 15, 2005 page 8 of 32

ALC (Automatic Level Control)

ALC is the input decay rate variable system. It has internal variable resistors of pin 8 (pin 23) by REC signal that is

inputted to pin 7 (pin 24).

Pin 17 is detector pin.

The signal input pin is pin 7 (pin 24). Resistor R1, R2 and capacitor C2, external components, for the input circuit are

commended as figure 4. There are requested to use value of the block diagram figure for performance maintenance of

S/N, T.H.D. etc.

Figure 5 shows the relation with R1 and C1 front input point and RECOUT.

ALC operation level acts for the center of +4.5 dB to standard level (453 mVrms).

Then, adopted maximum value circuit, ALC is operated by a large channel of signal.

ALC ON/OFF can switch it by pin 11. Please do ALC ON, after it does for one time ALC OFF inevitably, for ALC

time to start usefully, in order to reset ALC circuit.

453 mV

4.5 dB

Figure 5 ALC Operation Level