CH9294

The CH9294 is a kind of dual PLL clock generator intended for high frequency graphics applications. It also can be used in applications which requires multiple clocks, such as PC motherboards, disk drivers, CD-ROM systems and modems. The device provides separate memory clock (MCLK) and video clock (VCLK) outputs, and a 14.318 MHz reference clock output. Other input frequencies can be used to obtain different output frequencies. Internal loop filter elements minimize external part count. The STROBE pin should be tied high or left open if not used. FSx pins are latched on the falling edge of STROBE.

There are CH9294 features as follows: (1)generates 16 preset video clocks, 8 preset memory clocks, and buffers the reference frequency output; (2)built-in power supply conditioning circuitry provides excellent jitter performance and eliminates the need for an external VDD dropping resistor; (3)requires only two external components: one 14.318 MHz crystal and one 0.1F decoupling capacitor; (4)supports VGA, Super-VGA, XGA and 8514 graphic standards; (5)supports output frequencies up to 135 MHz; (6)drop-in replacement for ICS2494 and AV9194; (7)CMOS technology in 20-pin PDIP and SOIC; (8)5 V or 3.3 V supply.

The following is CH9294 absolute maximum ratings: (1)VDD, power supply voltage with respect to GND: -0.5 to +7.0 V; (2)VIN, input voltage on any pin with respect to GND: -0.5 to VDD+0.5 V; (3)TSTOR, storage temperature: -55 to +150. Then is about the DC specifications (operating conditions: Ta=0 to 70, VDD=5 V±5%): (1)VOH, output high voltage: 2.4 V min at VDD=4.75 V, IOH=4 mA; (2)VOL, output low voltage: 0.4 V max at VDD=4.75 V, IOL=8 mA; (3)VIH, input high voltage: 2.0 V min; (4)VIL, input low voltage: 0.8 V max; (5)IPU, input pull-up current: 5A typ and 20A max; (6)ILK, input leakage current: -10A min and 10A max; (7)IDD, operating current: 45 mA typ at VDD=5 V, VCLK=50 MHz, no load, MCLK=55 MHz, no load.