ZHCSDH8 March 2015 LMX2571
PRODUCTION DATA.
It is recommended to place 100 nF capacitor close to each of the power supply pins. If fractional spurs are a large concern, using a ferrite bead to each of these power supply pins may reduce spurs to a small degree.
VcpExt is the power supply pin for the 5-V charge pump. In PLL mode, the 5-V charge pump is active and a 5 V is required at VcpExt pin. In synthesizer mode, although the 5-V charge pump is not active, either a 3.3-V or 5-V supply is still needed at this pin.
Because LMX2571 has integrated LDOs, the requirement to external power supply is relaxed. In addition to LDO, LMX2571 is able to operate with DC-DC converter. The switching noise from the DC-DC converter would not affect performance of the LMX2571. Table 44 lists some of the suggested DC-DC converters.
PART NUMBER | TOPOLOGY | VIN | VOUT | IOUT | SWITCHING FREQUENCY |
---|---|---|---|---|---|
TPS560200 | Buck | 4.5 V to 17 V | 0.8 V to 6.5 V | 500 mA | 600 kHz |
TPS62050 | Buck | 2.7 V to 10 V | 0.7 V to 6 V | 800 mA | 1 MHz |
TPS62160 | Buck | 3 V to 17 V | 0.9 V to 6 V | 1000 mA | 2.25 MHz |
TPS562200 | Buck | 4.5 V to 17 V | 0.76 V to 7 V | 2000 mA | 650 kHz |
TPS63050 | Buck Boost | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 500 mA to 1 A | 2.5 MHz |