SEMICONDUCTOR TECHNICAL DATA
Not Recommended for New Designs
CMOS PLL Clock Driver
Programmable Frequency, Low Skew,
The MC88PL117 utilizes proven phase–locked loop clock driver
technology to create a large fan–out, multiple frequency and phase, low
skew clock driver. The 88PL117 provides the clock frequencies
necessary to drive systems using the PowerPC™ 601 microprocessor
and the Pentium™ microprocessor (see applications section for details).
A total of 14 high current, matched impedance outputs are available in 8
programmable output frequency and phase configurations. Output
frequencies are referenced to a system frequency, Q, and are available at
2X, 1X, and 1/2X the Q frequency. Four programmable input frequency
multiplication ratios can be programmed to provide outputs at 1X, 2X, and
4X the system frequency Q. Details on the programmable configurations
can be found in the applications section of this data sheet.
• Clock Driver for PowerPC 601 and Pentium Microprocessors
• 14 programmable outputs
• Maximum output–to–output skew of 500ps for a single frequency
• Maximum output–to–output skew of 500ps for multiple frequencies
• fMAX of 2X_Q = 120MHz
• One output with programmable phase capability
• ±36mA DC current outputs drive 50Ω transmission lines
• A lock indicator output (LOCK) goes high when steady–state
phase–lock is achieved
• OE/MR 3–state control
• Dedicated feedback output
• Two selectable clock inputs
• PLL enable pin for testability
• Dynamic Switch Between SYNC Inputs
52–LEAD PLASTIC LEADLESS
CHIP CARRIER (PLCC)
One output (QFEED) is dedicated for feedback. It is located physically close to the FEEDBACK input pin to minimize the
feedback line length. External delay (increased wire length) or logic can be inserted in the feedback path if necessary. Proper
termination of the feedback line is necessary for any line length over one inch.
One output is provided with up to eight selectable 1/8 or 1/4 period (45° or 90°) delay increments. Three control pins, ∅2, ∅1
and ∅0, program the eight increments; the increment/phase shift positions are shown in Table 3. in the applications section.
All outputs can be 3–stated (high impedance) during board–level testing with the OE/MR pin; the QFEED and LOCK outputs
will not be 3–stated, which allows the 88PL117 to remain in a phase–locked condition. Correct phase and frequency coherency
will be guaranteed one to two cycles after bringing the OE/MR pin high. The PLL_EN pin disables the PLL and gates the SYNC
input signal directly into the internal clock distribution network to provide low frequency testability. Two selectable SYNC inputs
(SYNC0 and SYNC1) are provided for clock redundancy or ease of testability. The device is guaranteed to lock to the new SYNC
input when the REF_SEL input is switched dynamically.
A phase–lock indicator output (LOCK) stays low when the part is out of lock (start–up, etc.) and goes high when steady–state
phase–lock is achieved. The lock indicator circuitry works reliably for VCO frequencies down to 55MHz. For VCO frequencies
less than 55MHz, no guarantees are offered for the lock indicator output.
The MC88PL117 VCO is capable of operating at frequencies higher than the output divider and feedback structures are able
to follow. When the VCO is in the mode described above, it is referred to as “runaway” and the device will not lock. The condition
usually occurs at power–up. To avoid runaway, it is recommended that the device be fully powered before a sync signal is
PowerPC is a trademark of International Business Machines Corporation.
© Motorola, Inc. 1997