122

Audio ICs

BU2614 / BU2614FS

FFrequency counter

(1)

Structure

(2)

How the frequency counter operates

When control data CT equals 1, the 20-bit counter and

the amp go into operation. When CT equals 0, input pull-

down and the counter are reset. Measuring time (gate

pulse) is selected (16ms / 32ms) on the basis of control

data GT. When control data CT equals 0, the counter is

reset.

(3)

Explanation of output data

How the unlock detection circuit operates

When control data GT equals 1, or CT equals 1, the un-

lock detection circuit goes into operation for 8ms. When

CT equals 1, the unlock detection circuits stops operating

before the frequency counter gate pulse is emitted.

When CT equals 0, or GT equals 0, the unlock detection

circuit is reset.