Philips Semiconductors Linear Products

Product specification

NE/SE567

Tone decoder/phase-locked loop

April 15, 1992

410

Figure 3. Sensitivity Adjust

567

567

567

DECREASE

SENSITIVITY

INCREASE

SENSITIVITY

V+

R

R

1

1

1

SILICON

DIODES FOR

TEMPERATURE

COMPENSATION

(OPTIONAL)

2.5k

1.0k

50k

C3

C3

C3

RB

RC

V+

DECREASE

SENSITIVITY

INCREASE

SENSITIVITY

RA

connected to pin 6 without affecting the CCO duty cycle or

temperature stability.

OPERATING PRECAUTIONS

A brief review of the following precautions will help the user achieve

the high level of performance of which the 567 is capable.

1. Operation in the high input level mode (above 200mV) will free

the user from bandwidth variations due to changes in the in-band

signal amplitude. The input

stage is now limiting, however, so that out-band signals or high

noise levels can cause an apparent bandwidth reduction as the

inband signal is suppressed. Also, the limiting action will create

in-band components from sub-harmonic signals, so the 567

signals are anticipated, they should be attenuated before

reaching the 567 input.

3. Maximum immunity from noise and out-band signals is afforded

operating mode. However, decreased loop damping causes the

worst-case lock-up time to increase, as shown by the Greatest

Number of Cycles Before Output vs Bandwidth graph.

4. Due to the high switching speeds (20ns) associated with 567

operation, care should be taken in lead routing. Lead lengths

should be kept to a minimum. The power supply should be

adequately bypassed close to the 567 with a 0.01

µF or greater

capacitor; grounding paths should be carefully chosen to avoid

ground loops and unwanted voltage variations. Another factor

which must be considered is the effect of load energization on

the power supply. For example, an incandescent lamp typically

draws 10 times rated current at turn-on. This can be somewhat

greater when the output stage is made less sensitive, rejection of

third harmonics or in-band harmonics (of lower frequency

signals) is also improved.

cause supply voltage fluctuations which could, for example, shift the

detection band of narrow-band systems sufficiently to cause

momentary loss of lock. The result is a low-frequency oscillation into

and out of lock. Such effects can be prevented by supplying heavy

load currents from a separate supply or increasing the supply filter

capacitor.

SPEED OF OPERATION

Minimum lock-up time is related to the natural frequency of the loop.

The lower it is, the longer becomes the turn-on transient. Thus,

When the signal is first applied, the phase may be such as to initially

drive the controlled oscillator away from the incoming frequency

rather than toward it. Under this condition, which is of course

unpredictable, the lock-up transient is at its worst and the theoretical

minimum lock-up time is not achievable. We must simply wait for the

transient to die out.

highest operating speeds for various band center frequencies. The

minimum rate at which digital information may be detected without

information loss due to the turn-on transient or output chatter is

about 10 cycles per bit, corresponding to an information transfer rate

Rf

Figure 4. Chatter Prevention

567

V+

8

Cf

LOWER VALUE OF Cf

RL

Rf*

10k

*OPTIONAL - PERMITS

C3

567

V+

8

200 TO

RL

RA

C3

1

1k

10k

567

V+

8

1

10k

Rf

RL

V+

200 TO 1k

RA

1

Figure 5. Skew Adjust

567

567

567

V+

R

R

2

2

1

SILICON

DIODES FOR

TEMPERATURE

COMPENSATION

(OPTIONAL)

2.5k

1.0k

50k

C2

C2

C2

RB

RC

V+

RA

RAISES fO

LOWERS fO

RAISES fO

RAISES fO

LOWERS fO