M65KG256AB datasheet(9/51 Pages) STMICROELECTRONICS

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M65KG256AB

2 Signal descriptions

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Signal descriptions

See Figure 1: Logic Diagram, and Table 1: Signal Names, for a brief overview of the signals

connected to this device.

2.1

Address Inputs (A0-A12)

The A0-A12 Address Inputs are used to select the row or column to be made active. If a row is

selected, all thirteen, A0-A12 Address Inputs are used. If a column is selected, only the nine

least significant Address Inputs, A0-A8, are used. In this latter case, A10 determines whether

Auto Precharge is used:

●

During a Read or Write operation:

–

If A10 is High (set to ‘1’), the Read or Write operation includes an Auto Precharge

cycle.

–

If A10 is Low (set to ‘0’), the Read or Write cycle does not include an Auto Precharge

cycle.

●

When issuing a Precharge command:

–

If A10 is Low, only the bank selected by BA1-BA0 will be precharged.

–

If A10 is High, all the banks will be precharged.

The address inputs are latched at the cross point of K rising edge and K falling edge.

2.2

Bank Select Address Inputs (BA0-BA1)

The Banks Select Address Inputs, BA0 and BA1, are used to select the bank to be made active

(see Table 2: Bank Selection using BA0-BA1).

When selecting the addresses, the device must be enabled, the Row Address Strobe, RAS,

must be Low, VIL, the Column Address Strobe, CAS, and W must be High, VIH.

2.3

Data Inputs/Outputs (DQ0-DQ15)

The Data Inputs/Outputs output the data stored at the selected address during a Read

operation, or to input the data during a write operation.

2.4

Chip Enable (E)

The Chip Enable input, E, activates the memory state machine, address buffers and decoders

when driven Low, VIL. When E is High, VIH, the device is not selected.

2.5

Column Address Strobe (CAS)

The Column Address Strobe, CAS, is used in conjunction with Address Inputs A8-A0 and BA1-

BA0, to select the starting column location prior to a read or write operation.

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