ICS84320-01K Datasheet, PDF (9/16 Pages) Integrated Circuit Systems – 780MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL LVPECL FREQUENCY SYNTHESIZER

Integrated
Circuit
Systems, Inc.
PRELIMINARY
ICS84320-01K
780MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
APPLICATION INFORMATION
POWER SUPPLY FILTERING TECHNIQUES
As in any high speed analog circuitry, the power supply pins
are vulnerable to random noise. The ICS84320-01K provides
separate power supplies to isolate any high switching
noise from the outputs to the internal PLL. V_CC, V_CCA, and V_CCO
should be individually connected to the power supply
plane through vias, and bypass capacitors should be
used for each pin. To achieve optimum jitter performance,
power supply isolation is required. Figure 2 illustrates how
a 24Ω resistor along with a 10µF and a .01µF bypass
capacitor should be connected to each V_CCA pin.
V_CC
V_CCA
3.3V
.01µF 24Ω
.01µF
10µF
FIGURE 2. POWER SUPPLY FILTERING
CRYSTAL INPUT INTERFACE
A crystal can be characterized for either series or parallel mode
operation. The ICS84320-01K has a built-in crystal oscillator
circuit.This interface can accept either a series or parallel crystal
without additional components and generate frequencies with
accuracy suitable for most applications. Additional accuracy can
be achieved by adding two small capacitors C1 and C2 as shown
in Figure 3.
X1
18pF Parallel Crystal
25
C1
18p
XTAL1
24
C2
22p
XTAL2
ICS84320-01
ICS84320-01K
Figure 3. CRYSTAL INPUT INTERFACE
84320AK-01
www.icst.com/products/hiperclocks.html
9
REV. A FEBRUARY 6, 2004