Dual PLL Frequency Synthesizer
Interfaces with Dual–Modulus Prescalers

The MC145149 contains two PLL Frequency Synthesizers which share a common serial data port and common reference oscillator. The device contains two 14–stage R counters, two 10–stage N counters, and two 7–stage A counters. All six counters are fully programmable through a serial port. The divide ratios are latched into the appropriate counter latch according to the last data bits (control bits) entered.
When combined with external low–pass filters and voltage controlled oscillators (VCOs), the MC145149 can provide all the remaining functions for two PLL frequency synthesizers operating up to the device’s frequency limit. For higher VCO frequency operation, a down mixer or dual–modulus prescaler can be used between the VCO and the synthesizer IC.

• Low Power Consumption Through Use of CMOS Technology
• Wide Operating Voltage Range: 3 to 9 V
• Operating Temperature Range: – 40 to + 85°C
• ÷ R Range = 3 to 16,383
• ÷ N Range = 3 to 1023
• ÷ A Range = 0 to 127
• Two “Linearized” Three–State Digital Phase Detectors with No Dead Zone
• Two Lock Detect Signals (LD1 and LD2)
• Two Open–Drain Port Expander Outputs (SW1 and SW2)
• Compatible with the Serial Peripheral Interface (SPI) on CMOS MCUs