1.1GHZ DUAL PLL

S1T8825

7

PRELIMINARY ( VER.2.1 )

CHARGE PUMP OUTPUT POLARITY (CP)

In normal operation, the CP should be “0”.

In reverse operation, the CP should be “1”.

Depending upon VCO characteristics, CP should be set accordingly;

When VCO characteristics are like (1), CP should be set to low

When VCO characteristics are like (2), CP should be set to high.

CHARGE PUMP OUTPUT CURRENT (CP1, CP2)

The S1T8825 includes a constant current output type charge pump circuit.

Output current is varied according to control bit “CP1” and “CP2”.

In order to get high speed lock-up, select the best charge pump output current.

Control Bit

Charge Pump

Output Current

CP1

CP2

0

0

± 100 µA

0

1

± 200 µA

1

0

± 400 µA

1

1

± 800 µA

(1)

(2)

VCO

Output

Frequency

VCO Characteristics

VCO Input Voltage