1996 Oct 10

16

Philips Semiconductors

Product specification

1.3 GHz universal bus-controlled

TV synthesizer

TSA5520; TSA5521

APPLICATION INFORMATION

Tuning amplifier

The tuning amplifier is capable of driving the varicap

voltage without an external transistor. The tuning voltage

output must be connected to an external load of 27 k

Ω

which is connected to the tuning voltage supply rail.

Figures 11 and 12 show a possible loop filter.

The component values depend on the oscillator

characteristics and the selected reference frequency.

Crystal oscillator

The crystal oscillator uses a 4 MHz crystal connected in

series with an 18 pF capacitor thereby operating in the

series resonance mode. Connecting the oscillator to the

supply voltage is preferred but it can, however, also be

connected to ground.

S = START, A = acknowledge and P = STOP. The sequence is as follows:

START + address byte + divider byte 1 + divider byte 2 + control byte + band switch byte + STOP.

For the complete sequence see Table 8 (sequence 1) or Table 9 (sequence 2).

Table 8

Complete sequence 1

Table 9

Complete sequence 2

Table 10 Divider bytes only sequence

Table 11 Control and band switch bytes only sequence

Table 12 Control byte only sequence

to the CE input.

Examples of 3-wire bus sequences (TSA5520; SW = OPEN)

The reference divider is automatically set to 512 unless RSB has been programmed to 0 during a 27-bit sequence.

S

C2

A

06A40A

CE

A08A

P

S

C2

A

CE

A08A06A40A

P

S

C2

A

06A40A

P

S

C2

A

CE

A08A

P

SC2A

CE

A

P

100011001000000000

0100101000101000000