ICS1562B
User Programmable Differential Output Graphics Clock Generator
ICS1562B
VCO GAIN
4
5
6
7
TSD
MAX FREQUENCY
120 MHz
200 MHz
260 MHz
*
Power Supplies and Decoupling
The
ICS1562B
has two VSS pins to reduce the effects of
package inductance. Both pins are connected to the same
potential on the die (the ground bus). BOTH of these pins
should connect to the ground plane of the video board as close
to the package as is possible.
The
ICS1562B
has a VDDO pin which is the supply of +5 volt
power to all output drivers. This pin should be connected to the
power plane (or bus) using standard high-frequency decou-
pling practice. That is, capacitors should have low series induc-
tance and be mounted close to the
ICS1562B.
The VDD pin is the power supply pin for the PLL synthesizer
circuitry and other lower current digital functions. We recom-
mend that RC decoupling or zener regulation be provided for
this pin (as shown in the recommended application circuitry).
This will allow the PLL to “track” through power supply
fluctuations without visible effects. See Figure 6 for typical
external circuitry.
*SPECIAL APPLICATION. Contact factory for custom product above
260 MHz.
•
Phase Detector Gain: For most graphics applications and
divider ranges, set P[1, 0] = 10 and set P[2] = 1. Under
some circumstances, setting the P[2] bit “on” can reduce
jitter. During 1562 operation at exact multiples of the
crystal frequency, P[2] bit = 0 may provide the best jitter
performance.
Board Test Support
It is often desirable to statically control the levels of the output
pins for circuit board test. The
ICS1562B
supports this through
a register programmable mode, AUXEN. When this mode is
set, two register bits directly control the logic levels of the
CLK+/CLK- pins and the LOAD pin. This mode is activated
when the S[0] and S[1] bits are both set to logic 1. See Register
Mapping for details.
Figure 6
6
IDT™ / ICS™
User Programmable Differential Output Graphics Clock Generator
6
ICS1562B
IDT [ INTEGRATED DEVICE TECHNOLOGY ]
