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COMMERCIALANDINDUSTRIALTEMPERATURERANGES

IDT5V993A

3.3V PROGRAMMABLE SKEW PLL CLOCK DRIVER TURBOCLOCK

EXTERNALFEEDBACK

By providing external feedback, the IDT5V993A gives users flexibility

with regard to skew adjustment. The FB signal is compared with the

input REF signal at the phase detector in order to drive the VCO. Phase

differences cause the VCO of the PLL to adjust upwards or downwards

accordingly.

NOTES:

1. The device may be operated outside recommended frequency ranges without damage, but functional operation is not guaranteed. Selecting the appropriate FS value based on

input frequency range allows the PLL to operate in its ‘sweet spot’ where jitter is lowest.

higher outputs when they are operated in their undivided modes. The frequency appearing at the REF and FB inputs will be the same as the VCO when the output connected

to FB is undivided. The frequency of the REF and FB inputs will be 1/2 or 1/4 the VCO frequency when the part is configured for a frequency multiplication by using a divided

output as the FB input.

3. Skew adjustment range assumes that a zero skew output is used for feedback. If a skewed Q output is used for feedback, then adjustment range will be greater. For example

An internal loop filter moderates the response of the VCO to the

phase detector. The loop filter transfer function has been chosen to

provide minimal jitter (or frequency variation) while still providing accu-

rate responses to input frequency changes.

FS = LOW

FS = MID

FS = HIGH

Comments

15 to 35MHz

25 to 60MHz

40 to 85 MHz

Max Adjustment:

±9.09ns

±9.23ns

±9.38ns

ns

±49°

±83°

±135°

Phase Degrees

±14%

±23%

±37%

% of Cycle Time

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—

—

—

—

—

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PLL PROGRAMMABLE SKEW RANGE AND RESOLUTION TABLE

CONTROL SUMMARY TABLE FOR FEEDBACK SIGNALS

nF1:0

Skew (Pair #1, #2)

Skew (Pair #3)

Divide by 2

LM

LH

ML

M M

Zero Skew

Zero Skew

MH

HL

HM

HH

Divide by 4

NOTE:

1.

LL disables outputs if TEST = MID and GND/

sOE = HIGH.