SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER operation noise lev

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SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER operation noise lev

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QS5931T SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER
SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER
operation noise level outputs outputs, output <250ps output skew, Q0-Q4 Outputs 3-state reset while OE/RST disable feature frequency testing Internal loop filter network Internal VCO/2 option Balanced drive outputs ±24mA 80MHz maximum frequency Available QSOP package
QS5931T
DESCRIPTION
QS5931T Clock Driver uses internal phase locked loop (PLL) lock skew outputs reference clock input. outputs available: Q/2. Careful layout design ensure <250ps skew between Q0-Q4, outputs. QS5931T includes internal filter which provides excellent jitter characteristics eliminates need external components. Various combinations feedback divide-by-2 path allow applications customized linear operation over wide range input SYNC frequencies. also disabled PLL_EN signal allow frequency testing. QS5931T designed cost sensitive highperformance computing systems, workstations, multi-board computers, networking hardware, mainframe systems. Several used parallel scattered throughout system guaranteed skew, system-wide clock distribution networks. QSOP package, QS5931T clock driver represents best value small form factor, highperformance clock management products. more information clock driver products, Application Note AN-227.
FUNCTIONAL BLOCK DIAGRAM
FEEDBACK PLL_EN FREQ_SEL
SYNC OE/RST
DETECTO FILTER
2000 Integrated Device Technology, Inc.
AUGUST 2000
DSC-5818/-
QS5931T SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER
CONFIGURATION
ABSOLUTE MAXIMUM RATINGS
Symbol Rating AVDD/VDD Supply Voltage Ground
Unit
Max. -0.5 -0.5 Vcc+0.5 +150
OE/RST FEEDBACK SYNC FREQ_SEL
20-8
PLL_EN
Input Voltage TSTG Maximum Power Dissipation 85°C) Storage Temperature Range
NOTE: Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS cause permanent damage device. This stress rating only functional operation device these other conditions above those indicated operational sections this specification implied. Exposure absolute maximum rating conditions extended periods affect reliability.
CAPACITANCE 1MHz,
Pins COUT Typ. Max. Unit
QSOP VIEW
DESCRIPTION
Name SYNC FREQ_SEL FEEDBACK OE/RST PLL_EN AVDD AGND Reference clock input frequency select. choosing optimal operating frequency depending input frequency. HIGH higher frequencies, lower frequencies. feedback input which connected either output. External feedback provides flexibility different output frequency relationships. Frequency Selection Table more information. Clock outputs Clock output. Matched phase, frequency half frequency. Output enable/asynchronous reset. Resets output registers. When outputs held tri-stated condition. When outputs enabled. enable. Enables disables PLL. Allows SYNC input single-stepped system debug. Power supply output buffers. Power supply phase lock loop other internal circuitries. Ground supply output buffers. Ground supply phase lock loop other internal circuitries. Description
OUTPUT FREQUENCY SPECIFICATIONS
Industrial: -40°C +85°C, AVDD/VDD 5.0V
Symbol FMAX_Q FMAX_Q/2 FMIN_Q FMIN_Q/2 Description Frequency, Frequency, Frequency, Frequency, Units
QS5931T SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER
FREQUENCY SELECTION TABLE
FREQ_SEL HIGH HIGH Output Used Feedback SYNC (MHz) (allowable range) Min. FMIN_Q/2 FMIN_Q FMIN_Q/2 FMIN_Q FMAX _Q/2 FMAX FMAX _Q/2 FMAX Output Frequency Relationships SYNC SYNC SYNC SYNC SYNC SYNC SYNC SYNC
NOTE: Operation specified SYNC frequency range guarantees that will operate optimal range 20MHz FMAX_Q Operation with Sync inputs outside specified frequency ranges result out-of-lock outputs. FREQ_SEL only affects frequency does affect output frequencies.
ELECTRICAL CHARACTERISTICS OVER OPERATING RANGE
Following Conditions Apply Unless Otherwise Specified: Industrial: -40°C +85°C, AVDD/VDD 5.0V
Symbol Parameter Input HIGH Voltage Input Voltage Output HIGH Voltage Output Voltage Input Hysteresis Output Leakage Current Input Leakage Current Conditions Guaranteed Logic HIGH Level Guaranteed Logic Level Min., -24mA Min., -100µA Min., 24mA Min., 100µA VOUT GND, Max., Outputs Disabled AVDD GND, AVDD Max. Min. Typ. Max. 0.45 Unit
POWER SUPPLY CHARACTERISTICS
Symbol IDDQ IDDD Parameter Quiescent Power Supply Current Power Supply Current Input HIGH Dynamic Power Supply Current Test Conditions Max., OE/RST LOW, SYNC LOW, outputs unloaded Max., 3.4V Max., Typ. Max. Unit mA/MHz
INPUT TIMING REQUIREMENTS
Symbol tPWC Description Maximum input rise fall times, 0.8V Input Clock Frequency, SYNC Duty Cycle, SYNC
Min.
Max. FMAX
Unit
Input clock pulse, HIGH
NOTES: Output Frequency Frequency Selection tables more detail allowable SYNC input frequencies different speed grades with different FEEDBACK FREQ_SEL combinations. Where pulse witdh implied less than tWPC limit, tWPC limit applies
QS5931T SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER
SWITCHING CHARACTERISTICS OVER OPERATING RANGE
Symbol tSKR tSKF tLOCK tPZH tPZL tPHZ tPLZ Parameter Output Skew Between Rising Edges, Q0-Q4 Output Skew Between Falling Edges, Q0-Q4 Pulse Width, Q0-Q4, outputs, 80MHz Cycle-to-Cycle Jitter
Min. TCY/2
Max. TCY/2 0.25
Unit
SYNC Input Feedback Delay SYNC Phase Lock
Output Enable Time, OE/RST HIGH Output Disable Time, OE/RST HIGH Output Rise/Fall Times, 0.8V
NOTES: Test Loads Waveforms test load termination. Skew specifications apply under identical environments (loading, temperature, VDD, device speed grade). Measured open loop mode PLL_EN Jitter characterized with output 20MHz. Frequency Selection Table information proper FREQ_SEL level specified input frequencies. measured device inputs 1.5V, output 80MHz.
QS5931T SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER
TEST LOADS WAVEFORMS
7.0V TPUT
TPUT
30pF
TEST CIRCUIT
1.0ns 1.0ns
TEST CIRCUIT
3.0V 2.0V 1.5V 0.8V 2.0V 1.5V 0.8V
INPUT TEST WAVEFORM
ABLE DISABLE
OUTPUT WAVEFORM
1.5V
INPU TPUT ALLY SWITC 1.5V 0.3V SWITC TPUT ALLY 1.5V 0.3V 3.5V
ENABLE DISABLE TIMES
TEST CIRCUIT used output enable/disable parameters. TEST CIRCUIT used other timing parameters.
QS5931T SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER
TIMING DIAGRAM
SYNC
FEEDBACK
NOTES: Timing Diagram applies output connected FEEDBACK. parameters measured 1.5V.
QS5931T SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER
OPERATION
Phase Locked Loop (PLL) circuit included QS5931T provides replication incoming SYNC clock signals. manipulation that signal, such frequency multiplying, performed digital logic following (see block diagram). advantage circuit provide effective zero propagation delay between output input signals. fact, adding delay circuits feedback path, `propagation delay' even negative! simplified schematic QS5931T circuit shown below:
SIMPLIFIED DIAGRAM QS5931T FEEDBACK
INPU PHASE DETECTO
phase difference between output input frequencies feeds which drives outputs. Whichever output back, will stabilize same frequency input. Hence, this true negative feedback closed loop system. most applications, output will optimally have zero phase shift with respect input. fact, internal loop filter QS5931T typically provides within 150ps phase shift between input output.
user wishes vary phase difference (typically compensate backplane delays), this most easily accomplished adding delay circuits feedback path. respective output used feedback will advanced amount delay feedback path. other outputs will retain their proper relationships that output.
QS5931T SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER
ORDERING INFORMATION
XXXX Device Type Speed Package
Quarter Size Outline Package (SO20-8)
MHz. max. frequency MHz. max. frequency MHz. max. frequency
5931T
Skew Clock Driver with Integrated Loop Filter
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SKEW CLOCK DRIVER WITH INTEGRATED LOOP FILTER operation noise lev

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