Z9960
Document #: 38-07087 Rev. *B Page 3 of 7
Overview
The Z9960 has an integrated PLL th at p r ov ide s low s k ew an d
low jitt er clock outputs for high-perform ance microp rocessors.
Three independent banks of seven outputs as well as an
independent PLL feedback output, FB_OUT, provide excep-
tional flexibility for possible output configurations. The PLL is
ensured stable operation given that the VCO is configured to
run between 200 MHz to 400 MHz. This allows a wide range
of output frequencies up to 200 MHz.
The phas e detec tor com pares the in put refere nce cl ock to th e
external feedback input. For normal operation, the external
feedback input, FB_IN, is connected to the feedback output,
FB_OU T. The inte rnal VCO is running at mult iples of the input
reference clock set by FB_SEL select inputs; refer to Table 1.
The VCO frequency is then divided down to provide the
required output frequencies.
Zero Delay Buffer
When used as a z ero d elay buf f er the Z99 60 w il l li ke ly be i n a
nested clock tree application. For these applications the
Z9960 offers a low-voltage PECL clock input as a PLL
referenc e. This allo ws the us er to use LVPECL as the primary
clock distribution device to take advantage of its far-superior
skew performance. The Z9960 then can lock onto the LVPECL
reference and translate with near zero delay to low skew
outputs.
By using one of the outputs as a feedback to the PLL, the
propagation delay through the device is eliminated. The PLL
works to align the output edge, with the input reference edge
thus producing a near-zero delay. The reference frequency
affects the static phase offset of the PLL and thus the relative
delay between the inputs and outputs. Because the static
phase of fset is a func tion of the referen ce clock, the Tpd of th e
Z9960 is a function of the configuration used.
Absolute Maximum Ratings[2]
Input Voltage Relative to VSS:..............................VSS – 0.3V
Input Voltage Relative to VDD:..............................VDD + 0.3V
Stora ge Tempe ratu re:.................... ...... ...... .-65°C to + 150°C
Operating Temperature: ............................... -40°C to + 85°C
Maximum ESD Protection............................................... 2kV
Maximum Power Supply:................................................5.5V
Maximum Input Current: .................................................± 20mA
This device contains circuitry to protect the inputs against
damage due to high st atic vo ltages or elec tric fie lds; ho wever,
precautions should be taken to avoid application of any
voltage higher than the maximum rated vol tages to this c ircuit.
For proper operation, VIN and VOUT should be constrained to
the range VSS < (VIN or VOUT) < VDD.
Unused inputs must always be tied to an appropriate logic
voltage level (either VSS or VDD).
Note:
2. The voltage on any input or I/O or pin cannot exceed the power pin during
power-up. Power supply sequencing is NOT required.
Function Table
Control Pin 0 1
REF_SEL TCLK PECL_CLK
AVDD PLL Bypass, Out puts Cont roll ed by OE # PLL Power
OE# Outputs Enabled Outputs Disabled (except FB_OUT)
SELA Output Bank A at VCO/2 Output Bank A at VCO/4
SELB Output Bank B at VCO/2 Output Bank B at VCO/4
SELC Output Bank C at VCO/2 Output Bank C at VCO/4
FB_SEL Feedback Output at VCO/8 Feedback Output at VCO/12