AL440B

AL440B

November 28, 2001

13

L

H

H

↑

Read address pointer is stopped. Output data is held. Read

address pointer will be reset to zero and output is high

impedance after RE goes low.

H

L

L

↑

Normal Read operation.

H

L

H

↑

Read address pointer increases. Output is high impedance.

(Data skipping function)

H

H

L

↑

Read address pointer is stopped. Output data is held.

H

H

H

↑

Read operation stopped. Read address pointer is stopped.

Output is high impedance.

/PLRTY = GND

RRST

RE

OE

RCK Function

H

H

H

↑

Read reset. The read pointer is reset to zero.

Data in the address 0 is output.

H

H

L

↑

Read reset. The read pointer is reset to zero.

Output is high impedance.

H

L

H

↑

Read address pointer is stopped. Output data is held. Read

address pointer will be reset to zero and data in the address 0 is

output after RE goes low.

H

L

L

↑

Read address pointer is stopped. Output data is held. Read

address pointer will be reset to zero and output is high

impedance after RE goes low.

L

H

H

↑

Normal Read operation.

L

H

L

↑

Read address pointer increases. Output is high impedance.

(Data skipping function)

L

L

H

↑

Read address pointer is stopped. Output data is held.

L

L

L

↑

Read operation stopped. Read address pointer is stopped.

Output is high impedance.

When the new data is read, the read address should be between 192 and 524,287 cycles after the write

address pointer, otherwise the output for new data is not guarantee.

11.6 IRDY, ORDY Flags

The IRDY, ORDY flags indicate the status of FIFO. The IRDY signal reports whether or not there is

space available for writing new data to the FIFO. An ORDY signal reports whether or not there is

valid new data available at output. The IRDY and ORDY signals only report the status of the address

pointer; they will not stop or affect the read/write operations. The following tables describe the

IRDY/ORDY functions under different operating polarities.

/PLRTY = VDD

Signal

State

Function

H

No more free space is available for new input data

IRDY

L

Memory space is available for new input data.

ORDY

H

No new data is available in FIFO memory.