Date: 03/10/2008

Programmable multi-output clock generators

Analog Devices launched a pair of multi-output clock-generation and distribution ICs AD9520 and AD9522, with the combination of device integration, low-noise, low-jitter performance and signal output flexibility.

The new devices include a 512-byte embedded EEPROM memory block, affording system engineers a programmable clock solution that can serve as both the source and system clock, which avoids the need of separate source clock.

Some of the other key features are:

1. In addition to the on-chip EEPROM and PLL the AD9520/2 integrates dividers, fan-out buffers, and a VCO that tunes from 1.4 GHz to 2.95 GHz.
2. An external 3.3-V/5-V VCO/VCXO (voltage-controlled crystal oscillator) of up to 2.4 GHz also can be used.
3. The PLL/VCO clock-generation circuitry boasts industry leading phase noise of -150dBc/Hz at a 10 kHz offset on a 200-MHz clock signal, while the clock distribution fanout channels feature ultra-low wideband jitter performance of 225 femtoseconds.
4. Two reference inputs allow glitch-free switchover for applications requiring redundant references, while a PLL holdover mode maintains the output frequency in the event of a lost reference signal.
5. Zero delay operation is available to ensure precise phase alignment between inputs and outputs.
6. The AD9520 offers 12 differential LVPECL (low-voltage positive emitter-coupled logic) outputs in four groups, each with a 1 to 32 divider and phase delay.
7. The AD9522 includes 12 differential LVDS (low-voltage differential signaling) outputs.
8. Both devices alternatively offer up to 24 single-ended CMOS output configurations up to 250 MHz.

Availability: The AD9520 is available now in production quantities.
The AD9522 is available for sampling and will be released in October.

Packaging: The AD9520 and AD9522 come in a 64-lead LFCSP package
Pricing: $12.65 per unit in 1K-unit quantities.

For more information, visit http: http://www.analog.com/AD9520