Low Power 32KHz Crystal Oscillator (CLN12FFC)
Crystal Oscillator pad macro that supports industry standard 32KHz crystal
· Uses standard CMOS transistors
· Crystal Oscillation Mode: Fundamental
· Power down option for IDDQ testing
· Oscillator by-pass mode option for logic testing
· Self-contained ESD protection structure
High end consumer and professional applications require crystals with a minimum number of external components. These applications typically operate under severe noise environment of large digital video processing chips. A standard crystal oscillator pad provided in commodity libraries induces high noise and jitter. Analog Bits has developed a unique low noise Crystal Oscillator macro based on a proprietary architecture that is in volume production in several high end graphics and multi-media applications. This differentiated architecture has earned outstanding reviews on high volume production boards.
Typical Usage and Block Diagram
Figure 1 shows the block diagram of the Crystal Oscillator Pad. The macro has a power down control bit that allows to enable a low current state for IDDQ testing. The macro has the inherent capability of bypassing the crystal oscillator circuit by directly feeding the XTAL_IN pin from an external clock generator. In that mode the external clock applied on XTAL_IN pin will go directly to the output (XOUT) of the crystal oscillator macro without any modification. The input threshold will be close to VDDA/2 in this bypassed mode.
A LOCK signal is provided to indicate a good crystal frequency is available. It goes high after it has counted a preset number of cycles with ENABLE high and PD low, and then it stays high until the next disable or powerdown.
Table 1: Specifications
Table 2: Pin Description
Deliverables and EDA Design Views