7

256 x 18, 512 x 18, 1,024 x 18, 2,048 x 18 and 4,096 x 18

COMMERCIALANDINDUSTRIAL

TEMPERATURERANGES

MARCH 2013

onthenextLOW-to-HIGHtransitionofRCLK. ThefirsttransitionofRCLKwill

presenttheemptyoffsetvaluetothedataoutputlines.ThenexttransitionofRCLK

willpresentthefulloffsetvalue.OffsetregistercontentcanbereadoutintheIDT

Standard mode only. It cannot be read in the FWFT mode.

SYNCHRONOUS vs ASYNCHRONOUS PROGRAMMABLE FLAG TIM-

ING SELECTION

The IDT72V205/72V215/72V225/72V235/72V245 can be configured

during the "Configuration at Reset" cycle described in Table 3 with either

asynchronous or synchronous timing for PAE and PAF flags.

If asynchronous PAE/PAF configuration is selected (as per Table 3), the

PAEisassertedLOWontheLOW-to-HIGHtransitionofRCLK.PAEisresetto

HIGHontheLOW-to-HIGHtransitionofWCLK.Similarly,thePAFisasserted

LOWontheLOW-to-HIGHtransitionofWCLKandPAFisresettoHIGHonthe

LOW-to-HIGHtransitionofRCLK.Fordetailtimingdiagrams,seeFigure13for

asynchronous PAE timing and Figure 14 for asynchronous PAF timing.

IfsynchronousPAE/PAFconfigurationisselected,thePAEisassertedand

updated on the rising edge of RCLK only and not WCLK. Similarly, PAF is

assertedandupdatedontherisingedgeofWCLKonlyandnotRCLK.Fordetail

timingdiagrams,seeFigure22forsynchronousPAEtimingandFigure23for

synchronousPAFtiming.

REGISTER-BUFFERED FLAG OUTPUT SELECTION

The IDT72V205/72V215/72V225/72V235/72V245 can be configured

duringthe"ConfigurationatReset"cycledescribedinTable4withsingle,double

ortripleregister-bufferedflagoutputsignals.Thevariouscombinationsavail-

able are described in Table 4 and Table 5. In general, going from single to

doubleortriplebufferedflagoutputsremovesthepossibilityofmetastableflag

indicationsonboundarystates(i.e,emptyorfullconditions).Thetrade-offisthe

addition of clock cycle delays for the respective flag to be asserted. Not all

combinationsof register-bufferedflagoutputsaresupported.Register-buffered

outputsapplytotheEmptyFlagandFullFlagonly. Partialflagsarenoteffected.

Table 4 and Table 5 summarize the options available.

Number of Words in FIFO

IDT72V205

IDT72V215

IDT72V225

IDT72V235

IDT72V245

FF PAF

HF PAE EF

00

0

0

0

H

H

H

L

L

HH

H

L

H

(n + 1) to 128

(n + 1) to 256

(n + 1) to 512

(n + 1) to 1,024

(n + 1) to 2,048

H

H

H

H

H

HH

L

H

H

(256-m)to255

(512-m)to511

(1,024-m)to1,023

(2,048-m)to2,047

(4,096-m)to4,095

H

L

L

H

H

256

512

1,024

2,048

4,096

L

L

L

H

H

TABLE 1 — STATUS FLAGS FOR IDT STANDARD MODE

TABLE 2 — STATUS FLAGS FOR FWFT MODE

Number of Words in FIFO

IDT72V205

IDT72V215

IDT72V225

IDT72V235

IDT72V245

IR PAF HF PAE OR

00

0

0

0

L

H

H

L

H

LH

H

L

L

(n + 2) to 129

(n + 2) to 257

(n + 2) to 513

(n + 2) to 1,025

(n + 2) to 2,049

L

H

H

H

L

LH

LH

L

(257-m) to 256

(513-m) to 512

(1,025-m) to 1,024

(2,049-m) to 2,048

(4,097-m) to 4,096

LL

L

H

L

257

513

1,025

2,049

4,097

H

L

L

H

L

NOTES:

1. n = Empty Offset (Default Values : IDT72V205 n = 31, IDT72V215 n = 63, IDT72V225/72V235/72V245 n = 127)

2. m = Full Offset (Default Values : IDT72V205 m = 31, IDT72V215 m = 63, IDT72V225/72V235/72V245 m = 127)

NOTES:

1. n = Empty Offset (Default Values : IDT72V205 n = 31, IDT72V215 n = 63, IDT72V225/72V235/72V245 n = 127)

2. m = Full Offset (Default Values : IDT72V205 m = 31, IDT72V215 m = 63, IDT72V225/72V235/72V245 m = 127)