FS8308 datasheet(10/15 Pages) ETC1

10 / 15 page

Advance Information

FS8308

Page 10

April 2003

Stand-by Mode

The stand-by mode for the PLL is entered by programming the PS bit to high. In the stand-

by mode, the XIN and FIN amplifiers, N-counter, and R-counter are stopped, as well as the

internal current bias for charge pump block, the N- and R-counters are also reset, and the

DO and DB outputs are set to the high impedance state. As long as voltage is supplied to

DD2, data loaded to the latches is kept. To exit from stand-by mode to normal operation,

the PS bit must be programmed to low.

Reference Crystal Oscillator Buffer Output (BO)

This IC provides a reference crystal oscillator buffer output intended to be used as a crys-

tal local oscillator to a 2nd mixer. The terminal is represented as BO. For cases to enhance

the buffer output swing, increasing V

DD1 will be an efficient way.

Filter Switch Control (SW)

Control of SW terminal by “SW” bit. This terminal is for switching time-constant of loop

filter. Output type of this terminal is open drain output. When constant of loop filter

doesn’t change by this switch, general open drain output is available. Note that there is an

internal 200

Ω resistor connected between and drain terminal and output pin.

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