LMX2354 Datasheet | National Semiconductor

Description The LMX2354 is part of a family of monolithic integrated fractional N/Integer N frequency synthesizers designed to be used in a local oscillator subsystem for a radio transceiver. It is fabricated using National’s 0.5 µ ABi C V silicon Bi CMOS process. The LMX2354 contains quadruple modulus prescalers along with modulo 15 or 16 fractional pensation circuitry in the RF divider. The LMX2354 provides a continuous divide ratio of 80 to 32767 in 16/17/20/21 (1.2 GHz- 2.5 GHz) fractional mode and 40 to 16383 in 8/9/12/13 (550 MHz- 1.2 GHz) fractional mode. The IF circuitry for the LMX2354 contains an 8/9 prescaler, and is fully programmable. Using a fractional N phase locked loop technique, the LMX2354 can generate very stable low noise control signals for UHF and VHF voltage controlled oscillators (VCOs). For the RF PLL, a highly flexible 16 level programmable charge pump supplies output current magnitudes from 100 µA to 1.6 m A. Two unmitted CMOS outputs can be used to provide external control signals, or configured to Fast Lock mode. Serial data is transferred into the LMX2354 via a three wire interface (Data, LE, Clock). Supply voltage can range from 2.7V to 5.5V. The LMX2354 family features very low current consumption; typically LMX2354 (2.5 GHz) - 7.0 m A. The LMX2354 are available in a 24-pin TSSOP surface mount plastic package and 24-pin CSP. Features n n n n n n n Pin patible/functional equivalent to the LMX2350 Enhanced Low Noise Fractional Engine 2.7V to 5.5V operation Low current consumption LMX2354: ICC = 7 m A typical at 3V Programmable or logical power down mode: ICC = 5 µA typical at 3V Modulo 15 or 16 fractional RF N divider supports ratios of 1, 2, 3, 4, 5, 8, 15, or 16 Programmable charge pump current levels RF 100 µA to 1.6 m A in 100 µA steps IF 100 µA or 800 µA Digital filtered lock detect Available in 24-pin TSSOP and 24-pin CSP n n Applications n n n n n Portable wireless munications (PCS/PCN, cordless) Dual mode cellular telephone systems...