The LMX2377U device is a high performance frequency synthesizer with integrated dual modulus prescalers. The LMX2377U device is designed for use as a local oscillator for the first and second RF of a dual conversion radio transceiver. A 16/17 or a 32/33 prescale ratio can be selected for the Main synthesizer. An 8/9 or a 16/17 prescale ratio can be selected for the Aux synthesizer. Using a proprietary digital phase lock technique, the LMX2377U device generates very stable, low noise control signals for UHF and VHF voltage controlled oscillators. Both the Main and Aux synthesizers include a two-level programmable charge pump. The Main synthesizer has dedicated Fastlock circuitry. Serial data is transferred to the devices via a three-wire interface (Data, LE, Clock). The low voltage logic interface allows connection to 1.8V devices. Supply voltages from 2.7V to 5.5V are supported. The LMX2377U features ultra low current consumption, typically 3.5 mA at 3.0V. The LMX2377U devices are available in 20-Pin TSSOP, 24-Pin CSP, and 20-Pin UTCSP surface mount plastic packages.