8

COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES

IDT72V295/72V2105 3.3V HIGH DENSITY CMOS

Number of

Words in

FIFO

0

(n+1) to 65,536

65,537 to (131,072-(m+1))

131,072

0

(n+1) to 131,072

131,073 to (262,144-(m+1))

262,144

TABLE II

 STATUS FLAGS FOR FWFT MODE

IDT72V295

IDT72V2105

FF PAF HF PAE EF

HH

HL

L

HH

HL

H

HH

H

H

H

HH

L

H

H

HL

L

H

H

LL

LH

H

TABLE I

 STATUS FLAGS FOR IDT STANDARD MODE

4668 drw 05

0

(n+2) to 65,537

(131,073-m)

(2)

to 131,072

131,073

0

(n+2) to 131,073

131,074 to (262,145-(m+1))

(262,145-m)

(2)

to 262,144

262,145

IR PAF HF PAE OR

LH

H

L

H

LH

H

L

L

L

H

HHL

LH

L

H

L

LLL

H

L

HL

L

H

L

IDT72V295

IDT72V2105

Number of

Words in

FIFO

(

1)

65,538 to (131,073-(m+1))

NOTES:

1. n = Empty Offset, Default Values: n = 127 when parallel offset loading is selected or n = 1,023 when serial offset loading is selected.

2. m = Full Offset, Default Values: m = 127 when parallel offset loading is selected or m = 1,023 when serial offset loading is selected.

NOTES:

1. n = Empty Offset, Default Values: n = 127 when parallel offset loading is selected or n = 1,023 when serial offset loading is selected.

2. m = Full Offset, Default Values: m = 127 when parallel offset loading is selected or m = 1,023 when serial offset loading is selected.

PROGRAMMING FLAG OFFSETS

Full and Empty Flag offset values are user programmable. The

IDT72V295/72V2105 has internal registers for these offsets. Default set-

tings are stated in the footnotes of Table 1 and Table 2. Offset values can

be programmed into the FIFO in one of two ways; serial or parallel loading

method. The selection of the loading method is done using the

LD (Load)

pin. During Master Reset, the state of the

LDinput determines whether serial

or parallel flag offset programming is enabled. A HIGH on

LDduring Master

Reset selects serial loading of offset values and in addition, sets a default

PAE offset value of 3FFH (a threshold 1,023 words from the empty

boundary), and a default

PAFoffset value of 3FFH (a threshold 1,023 words

from the full boundary). A LOW on

LD during Master Reset selects parallel

loading of offset values, and in addition, sets a default

PAE offset value of

07FH (a threshold 127 words from the empty boundary), and a default

PAF

offset value of 07FH (a threshold 127 words from the full boundary). See

Figure 3, Offset Register Location and Default Values.

In addition to loading offset values into the FIFO, it also possible to read

the current offset values. It is only possible to read offset values via parallel

read.

Figure 4, Programmable Flag Offset Programming Sequence, summa-

rizes the control pins and sequence for both serial and parallel programming

modes. For a more detailed description, see discussion that follows.

The offset registers may be programmed (and reprogrammed) any time

after Master Reset, regardless of whether serial or parallel programming

has been selected.