Silan

Semiconductors

SC5260

HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD

Rev: 1.0

2000.12.31

6

3) Single Resistor Oscillator

The built-in oscillator circuitry of SC5260 allows a precision oscillator to be constructed by connecting an external

resistor between OSC and VCC pins. For SC5270 (or SC5272) to decode correctly the received waveform, the

oscillator frequency of SC5270 (or SC5272) must be 1/16~4 (or 1/16~1/4) times that of the transmitting SC5260.

The typical oscillator frequency of SC5270, and SC5272 are shown below:

Encoder (SC5260) OSC Frequency

Decoder (SC5270) OSC Frequency

400

300

250

200

100

500

1234

56789

10

Voltage (Volts)

R=820K

R=1M

R=2M

2

4

6

8

10

12

Voltage (Vcc)

0

20

40

60

80

100

120

140

160

180

0

OSC Resistor = 510K Ohms

OSC Resistor = 1.0M Ohms

OSC Resistor = 1.2M Ohms

OSC Resistor = 2.2M Ohms

Decoder (SC5272) OSC Frequency

1000

100

10

369

12

15

Voltage

R=100K

R=240K

R=510K

R=1M

R=2M

Suggested oscillator resistor values are shown below.

SC5260

SC5270

SC5272

820k

â

510k

â

1M

â

1M

â

620k

â

1.2M

â

2M

â

1.2M

â

2.2M

â