Fig. 1 Functional Block Diagram
ASNT8052-PQB is a clock multiplication unit (CMU) with a dual-range phase-locked loop (PLL) incorporating high-speed voltage-controlled oscillators (VCOs). The part features several control functions shown in Table 1 within the part’s datasheet.
One of the two frequency ranges can be selected by the control signal off12g. In the main operational mode, the IC shown in Fig. 1 accepts a low-speed reference clock cr16p/cr16n with the frequency f/16 and converts it into a high-speed output clock cho with the selectable frequency f or f/2 and a low-speed output clock clo with the frequency f/16. The frequency of the high-speed clock is selected through the external 3-state control signal offcho that can also disable the clock output buffer.
One of four 90° shifted phases of the low-speed output clock with the frequency f/16 can be selected by control signals phs1 and phs2. When operating in the closed-loop mode, the PLL requires an external loop filter connected to pins ftr1p and ftr1n. The output signal loln indicates the locked or unlocked state of the PLL. The PLL also supports an open-loop mode of operation with its selected VCO controlled externally by voltages applied to the filter pins ftr1p and ftr1n. The chip can operate as a divider by 16 of the input high-speed clock cep/cen if the PLL is disabled by the control signal offpll. The part makes use of a single +3.3V power supply and is characterized for operation from −25°C to 125°C of junction temperature.