17

µPC2533

2.7

Station Detector Circuit Block

Fig. 2-7 Station Detector Circuit Block

The configration station detector (SD) circuit block is shown in Fig. 2-7.

The SD circuit stops scanning or seeking when a broadcast wave is received when auto scanning or seek tuning.

Since the

µPC2533 has two outputs (DC high/low signal (open collector) and AC IF signal (f = 450 kHz)), it can be

used according to DTS (digital tuning system) type. Input the SD request signal from DTS to pin 5.

The SD sensitivity setting methods of the

µPC2533GS-01 and µPC2533GS-02 differ.

With the

µPC2533GS-01, SD sensitivities in the IF counter output system and in the high/low output system are

set by external resistor between pin 7 and GND and by external resistor between pin 9 and GND.

With the

µPC2533GS-02, SD sensitivities in both the IF counter output system and high/low output system are set

by external resistor between pin 7 and GND (refer to Fig. 2-6).

Table 2-1 SD Sensitivity Setting Examples

Value of Resistor between Pin 9 or Pin 7 and GND

SD Sensitivity (AC, DC)

51 k

Ω

27 dB

µV

24 k

Ω

29 dB

µV

10 k

Ω

33 dB

µV

+

–

–

+

–

+

10

5

6

8

1.0 V

ON/OFF

1.0 V

Detection comparator 1

Detection comparator 2

From signal meter

circuit (Fig. 2-6)

To time constant

switchover circuit

(Fig. 2-6)

From DTS (request)

SD output

(Active high)

SD AC output

450kHz IF input

(from T3)