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M672061H

4144K-AERO-04/07

Expansion In (XI)

This input is a dual-purpose pin. Expansion In (XI) is connected to GND to indicate an

operation in the single device mode. Expansion In (XI) is connected to Expansion Out

(XO) of the previous device in the Depth Expansion or Daisy Chain modes.

Full Flag (FF)

The Full Flag (FF) will go low, inhibiting further write operations when the write pointer is

one location less than the read pointer, indicating that the device is full. If the read

pointer is not moved after Reset (RS), the Full Flag (FF) will go low after 16384 writes.

Empty Flag (EF)

The Empty Flag (EF) will go low, inhibiting further read operations when the read pointer

is equal to the write pointer, indicating that the device is empty.

Expansion Out/Half-full

Flag (XO/HF)

This is a dual-purpose output. In the single device mode, when Expansion In (XI) is con-

nected to ground, this output acts as an indication of a half-full memory.

The M672061H offers a variable offset for the Half Full condition. The offset is loaded

into a register during a reset cycle. When RS is low, the Programmable Half Full Flag

loaded during the reset cycle, the default offset will be the half of the total memory of the

device.

The Programmable Half-Full Flag (PHF) will be set to low and will remain set until the

difference between the write and read pointers is less than or equal to the Programma-

ble offset (if the Half Full Flag register has been loaded during the reset cycle) or the half

of the total memory (if the Half Full register has not been loaded during the reset cycle).

After half the memory is filled and on the falling edge of the next write operation, the

Half-Full Flag (HF) will be set to low and will remain set until the difference between the

write and read pointers is less than or equal to half of the total memory of the device.

The Half-Full Flag (HF) is then reset by the rising edge of the read operation.

In the Depth Expansion Mode, Expansion In (XI) is connected to Expansion Out (XO) of

the previous device. This output acts as a signal to the next device in the Daisy Chain by

providing a pulse to the next device when the previous device reaches the last memory

location.

DATA output for 9-bit wide data. This data is in a high impedance condition whenever

Read (R) is in a high state.