STUW81300 datasheet(30/63 Pages) STMICROELECTRONICS

30 / 63 page

Circuit description

STuW81300

30/63

DS11314 Rev 7

change, is performed in a very short time (~13 ms) minimizing the impact on the overall PLL

switching time.

Once the correct VCO and sub-band are selected the normal PLL operations are resumed.

The VCO core can be supplied (pin#3) from 3.3 V to 4.5 V; the LDO_4V5 (programmable to

4.5 V and 3.3 V) is used for this purpose. Furthermore, the amplitude of oscillation, which

trades current consumption with phase-noise performance is 3-bit programmable (ST4

ranges of the oscillation amplitude for each available supply setting. In order to achieve the

best phase-noise performance, the maximum allowed amplitude setting is recommended.

VCO calibration auto-restart feature

The VCO calibration auto-restart feature, once activated, allows the calibration procedure to

be restarted when an event that moves the PLL into an unlock condition has occurred

(trigger on ‘1’ to ‘0’ transition of the lock detector signal).

This feature can be enabled through the EN_AUTOCAL bit (ST6 Register) and requires

proper setting of the lock detector parameters (LD_PREC and LD_COUNT, ST4 Register),

in order to avoid any unwanted transition of the lock detector signal during the transient time

required by the PLL to lock the VCO at the desired frequency.

Note:

This feature is not available on product code STUW81300-1T, STUW81300-1TR.

STUW81300 Datasheet(PDF) 30 Page - STMicroelectronics