PLL FREQUENCY SHNTHESIZER FOR PAGER

S5T8808A

7

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Ex 1) In case of 14-bits program, Fc = 325.300MHz, Multiplier = 4, Fin = 75.975MHz

[Fin Freq. / Ref. Frequ.] = 75.975MHz / 6.25kHz = 12156

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According to the above equation, 12156/4(P) = 3039 & left = 0 that means, Swallow CNT value is “0”, Main

CNT value is “3039”.

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The PMC bit is Program Control Bit, if [0], the N-Counter will be Enabled.

Table 2. R-Counter Register Program Scheme (17 bits)

Bit

Bit 16 (RD 13) ~ Bit 3 (RD 0)

Bit 2

Bit 1

Bit 0 (LSB)

Name

RefD

FRC

FnFr

PMC

Description

Ref. Program

Data (RD 13 ~ RD 0)

Control Mode

Program mode

control

Function

14 Bit Programmable

Ref. R-Counter

0: No FRC (OSCI/4R)

1: FRC (OSCI/R)

0: Fn, Fr function

1: Fn, Fr Low

0: Rx. N-Counter

1: Ref. R-Counter

Table 3. Control Mode

FRC

FnFr

Fn (Pin 14)

Fr (Pin 15)

0

0

Fn out (Fin / N counter)

Fr out (OSCI / 4 x R)

0

1

LOW

LOW

1

0

Fn out (Fin / N-counter)

Fr out (OSCI / R)

1

1

LOW

LOW

0

0

1

0

1

1

1

1

0

1

1

1

1

1

0

0

0

MSB

LSB

2

13

2

0

2

1

2

0

Main CNT 14 - bits

Swallow CNT 2-bits

PMC bit