MC88LV915TFN

MC88LV915TFN Datasheet

Order Number MC88LV915T/D Rev 3, 08/2001

Part	Datasheet
MC88LV915TFN	MC88LV915TFN (pdf)

Related Parts	Information
MC88LV915TFNR2	MC88LV915TFNR2
MC88LV915TEI	MC88LV915TEI

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MOTOROLA SEMICONDUCTOR TECHNICAL DATA Low Voltage Low Skew CMOS PLL Clock Driver, 3-State The MC88LV915T Clock Driver utilizes loop technology to lock its low skew outputs’ frequency and phase onto an input reference clock. It is designed to provide clock distribution for high performance PC’s and workstations. The PLL allows the high current, low skew outputs to lock onto a single clock input and distribute it with essentially zero delay to multiple components on a board. The PLL also allows the MC88LV915T to multiply a low frequency input clock and distribute it locally at a higher 2X system frequency. Multiple 88LV915’s can lock onto a single reference clock, which is ideal for applications when a central system clock must be distributed synchronously to multiple boards see Figure 4 on Page MC88LV915T LOW SKEW CMOS PLL CLOCK DRIVER Five “Q” outputs are provided with less than 500 ps skew between their rising edges. The Q5 output is inverted 180° phase shift from the “Q” outputs. The 2X_Q output runs at twice the “Q” output frequency, while the Q/2 runs at 1/2 the “Q” frequency. The VCO is designed to run optimally between 20 MHz and the 2X_Q Fmax specification. The wiring diagrams in Figure 2 detail the different feedback configurations which create specific input/output frequency relationships. Possible frequency ratios of the “Q” outputs to the SYNC input are 2:1, 1:1, and The FREQ_SEL pin provides one bit programmable in the feedback path of the PLL. It selects between and of the VCO before its signal reaches the internal clock distribution section of the chip see the block diagram on page In most applications FREQ_SEL should be held high If a low frequency reference clock input is used, holding FREQ_SEL low ÷2 will allow the VCO to run in its optimal range >20MHz . In normal operation the PLL_EN pin is held high. Pulling the PLL_EN pin low disables the VCO and puts the 88LV915T in a static “test mode”. In this mode there is no frequency limitation on the input clock, which is necessary for a low frequency board test environment. The second SYNC input can be used as a test clock input to further simplify testing see detailed description on page Pulling the OE/RST pin low puts the clock outputs 2X_Q, Q5 and Q/2 into a high impedance state After the OE/RST pin goes back high Q5 and Q/2 will be reset in the low state, with 2X_Q being the inverse of the selected SYNC input. Assuming PLL_EN is low, the outputs will remain reset until the 88LV915 sees a SYNC input pulse. A lock indicator output LOCK will go high when the loop is in phase and frequency lock. The LOCK output will go low if is lost or when the PLL_EN pin is low. The LOCK output will go high no later than 10ms after the 88LV915 sees a SYNC signal and full 5V VCC. Features • Five Outputs with Skew < 500 ps each being phase and frequency locked to the SYNC input • The phase variation from between the SYNC and FEEDBACK inputs is less than 550 ps derived from the tPD specification, which defines the skew • Input/Output frequency ratios of 1:2, 1:1, and 2:1 are available • Input frequency range from 5MHz 2X_Q FMAX spec. • Additional outputs available at 2X and +2 the system “Q” frequency. Also a Q 180° phase shift output available • All outputs have ±36 mA drive equal high and low at CMOS levels, and can drive either CMOS or TTL inputs. All inputs are compatible. ±88mA IOL/IOH specifications guarantee transmission line switching on the incident edge • Test Mode pin PLL_EN provided for low frequency testing. Two selectable CLOCK inputs for test or redundancy purposes. All outputs can go into high impedance for board test purposes • Lock Indicator LOCK accuracy indicates a state Yield Surface Modeling and YSM are trademarks of Motorola, Inc. Motorola, Inc. 2001 Pinout PLCC Top View OE/RST VCC Q5 GND Q4 VCC 2X_Q 4 3 2 1 28 27 26 FEEDBACK 5 25 Q/2 REF_SEL 6 24 GND SYNC[0] 7 23 Q3 VCC AN 8 RC1 9 22 VCC 21 Q2 GND AN 10 20 GND SYNC[1] 11 19 LOCK 12 13 14 15 16 17 18 FREQ_SEL GND Q0 VCC Q1 GND PLL_EN FN SUFFIX PLASTIC PLCC CASE PIN SUMMARY Pin Name Num Function SYNC[0] 1 Input Reference clock input

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MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

Low Voltage Low Skew CMOS PLL Clock Driver, 3-State

The MC88LV915T Clock Driver utilizes loop technology to lock its low skew outputs’ frequency and phase onto an input reference clock. It is designed to provide clock distribution for high performance PC’s and workstations.

The PLL allows the high current, low skew outputs to lock onto a single clock input and distribute it with essentially zero delay to multiple components on a board. The PLL also allows the MC88LV915T to multiply a low frequency input clock and distribute it locally at a higher 2X system frequency. Multiple 88LV915’s can lock onto a single reference clock, which is ideal for applications when a central system clock must be distributed synchronously to multiple boards see Figure 4 on Page

MC88LV915T

LOW SKEW CMOS PLL CLOCK DRIVER

Five “Q” outputs are provided with less than 500 ps skew between their rising edges. The Q5 output is inverted 180° phase shift from the “Q” outputs. The 2X_Q output runs at twice the “Q” output frequency, while the Q/2 runs at 1/2 the “Q” frequency.

The VCO is designed to run optimally between 20 MHz and the 2X_Q Fmax specification. The wiring diagrams in Figure 2 detail the different feedback configurations which create specific input/output frequency relationships. Possible frequency ratios of the “Q” outputs to the SYNC input are 2:1, 1:1, and

The FREQ_SEL pin provides one bit programmable in the feedback path of the PLL. It selects between and of the VCO before its signal reaches the internal clock distribution section of the chip see the block diagram on page In most applications FREQ_SEL should be held high If a low frequency reference clock input is used, holding FREQ_SEL low ÷2 will allow the VCO to run in its optimal range >20MHz .

In normal operation the PLL_EN pin is held high. Pulling the PLL_EN pin low disables the VCO and puts the 88LV915T in a static “test mode”. In this mode there is no frequency limitation on the input clock, which is necessary for a low frequency board test environment. The second SYNC input can be used as a test clock input to further simplify testing see detailed description on page

Pulling the OE/RST pin low puts the clock outputs 2X_Q, Q5 and Q/2 into a high impedance state After the OE/RST pin goes back high Q5 and Q/2 will be reset in the low state, with 2X_Q being the inverse of the selected SYNC input. Assuming PLL_EN is low, the outputs will remain reset until the 88LV915 sees a SYNC input pulse.

A lock indicator output LOCK will go high when the loop is in phase and frequency lock. The LOCK output will go low if is lost or when the PLL_EN pin is low. The LOCK output will go high no later than 10ms after the 88LV915 sees a SYNC signal and full 5V VCC.

Features
• Five Outputs with Skew < 500 ps each being phase and frequency locked to the SYNC input
• The phase variation from between the SYNC and FEEDBACK inputs is less than 550 ps derived from the tPD
specification, which defines the skew
• Input/Output frequency ratios of 1:2, 1:1, and 2:1 are available
• Input frequency range from 5MHz 2X_Q FMAX spec.
• Additional outputs available at 2X and +2 the system “Q” frequency. Also a Q 180° phase shift output available
• All outputs have ±36 mA drive equal high and low at CMOS levels, and can drive either CMOS or TTL inputs. All inputs are
compatible. ±88mA IOL/IOH specifications guarantee transmission line switching on the incident edge
• Test Mode pin PLL_EN provided for low frequency testing. Two selectable CLOCK inputs for test or redundancy purposes.

All outputs can go into high impedance for board test purposes
• Lock Indicator LOCK accuracy indicates a state Yield Surface Modeling and YSM are trademarks of Motorola, Inc.

Motorola, Inc. 2001

Pinout PLCC Top View

OE/RST VCC Q5 GND Q4 VCC 2X_Q
4 3 2 1 28 27 26

FEEDBACK 5
25 Q/2

REF_SEL 6
24 GND

SYNC[0] 7
23 Q3

VCC AN 8 RC1 9
22 VCC 21 Q2

GND AN 10
20 GND

SYNC[1] 11
19 LOCK
12 13 14 15 16 17 18

FREQ_SEL GND Q0 VCC Q1 GND PLL_EN

FN SUFFIX PLASTIC PLCC CASE

PIN SUMMARY

Pin Name Num

Function

SYNC[0]
1 Input Reference clock input

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Datasheet ID: MC88LV915TFN 635502