7

Commercial And Industrial Temperature Range

IDT72801/728211/72821/72831/72841/72851

LDA

LDA

LDA

LDA

LDA WENA1

WENA1

WENA1

WENA1

WENA1

WCLKA

OPERATION ON FIFO A

LDB

LDB

LDB

LDB

LDB WENB1

WENB1

WENB1

WENB1

WENB1

WCLKB

OPERATION ON FIFO B

00

Empty Offset (LSB)

Empty Offset (MSB)

Full Offset (LSB)

Full Offset (MSB)

0

1

No Operation

1

0

Write Into FIFO

1

1

No Operation

Figure 3. Offset Register Formats and Default Values for the A and B FIFOs

Figure 2. Writing to Offset Registers for FIFOs A and B

A read and write should not be performed simultaneously to the offset

registers.

OUTPUTS:

Full Flag (

FFA, FFB) — FFA (FFB) will go LOW, inhibiting further write

operations, when Array A (B) is full. If no reads are performed after reset,

FFA

(

FFB) will go LOW after 256 writes to the IDT72801's FIFO A (B); 512 writes

totheIDT72811'sFIFOA(B);1,024writestotheIDT72821'sFIFOA(B);2,048

writes to the IDT72831's FIFO A (B); 4,096 writes to the IDT72841's FIFO A

(B); or 8,192 writes to the IDT72851's FIFO A (B).

FFA(FFB)issynchronizedwithrespecttotheLOW-to-HIGHtransitionofthe

Write Clock WCLKA (WCLKB).

Empty Flag (

EFA, EFB) —EFA(EFB)willgoLOW,inhibitingfurtherread

operations, when the read pointer is equal to the write pointer, indicating that

Array A (B) is empty.

EFA(EFB)is synchronizedwithrespecttotheLOW-to-HIGHtransitionof

the Read Clock RCLKA (RCLKB).

87

0

Empty Offset (LSB) Reg.

Default Value 007H

80

Full Offset (LSB) Reg.

Default Value 007H

7

80

Empty Offset (LSB)

Default Value 007H

80

Full Offset (LSB)

Default Value 007H

72801 - DUAL 256 x 9

72811 - DUAL 512 x 9

7

7

80

(MSB)

1

00

87

0

Empty Offset (LSB) Reg.

Default Value 007H

80

Full Offset (LSB) Reg.

Default Value 007H

7

80

Empty Offset (LSB)

Default Value 007H

80

Full Offset (LSB)

Default Value 007H

72831 - DUAL 2,048 x 9

72851 - DUAL 8,192 x 9

7

7

80

80

(MSB)

0

2

(MSB)

0

3

80

80

(MSB)

0

2

(MSB)

0

3

80

8

0

80

(MSB)

1

0

3034 drw 04

80

Empty Offset (LSB)

Default Value 007H

80

Full Offset (LSB)

Default Value 007H

72841 - DUAL 4,096 x 9

7

7

80

(MSB)

0

4

80

(MSB)

0

4

80

Empty Offset (LSB)

Default Value 007H

80

Full Offset (LSB) Reg.

Default Value 007H

72821 - DUAL 1,024 x 9

7

7

80

(MSB)

0

1

80

(MSB)

0

1

NOTE:

1. For the purposes of this table,

2. The same selection sequence applies to reading from the registers.

RENA1 and

RENA2 (RENB1 and RENB2) are enabled and read is performed on the LOW-to-

HIGH transition of RCLKA (RCLKB).