M58LR128HT datasheet(47/112 Pages) STMICROELECTRONICS

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M58LR128HT, M58LR128HB

Read modes

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7.2.1

Synchronous Burst Read Suspend

A Synchronous Burst Read operation can be suspended, freeing the data bus for other

higher priority devices. It can be suspended during the initial access latency time (before

data is output) or after the device has output data. When the Synchronous Burst Read

operation is suspended, internal array sensing continues and any previously latched internal

data is retained. A burst sequence can be suspended and resumed as often as required as

long as the operating conditions of the device are met.

A Synchronous Burst Read operation is suspended when Chip Enable, E, is Low and the

current address has been latched (on a Latch Enable rising edge or on a valid clock edge).

The Clock signal is then halted at VIH or at VIL, and Output Enable, G, goes High.

When Output Enable, G, becomes Low again and the Clock signal restarts, the

Synchronous Burst Read operation is resumed exactly where it stopped.

WAIT being gated by E, it will remain active and will not revert to high impedance when G

goes High. So if two or more devices are connected to the system’s READY signal, to

prevent bus contention the WAIT signal of the M58LR128HT/B should not be directly

connected to the system’s READY signal.

WAIT will revert to high-impedance when Chip Enable, E, goes High.

See Table 24: Synchronous Read AC characteristics, and Figure 13: Synchronous Burst

Read Suspend AC waveforms, for details.

7.3

Single Synchronous Read mode

Single Synchronous Read operations are similar to Synchronous Burst Read operations

except that the memory outputs the same data to the end of the operation.

Synchronous Single Reads are used to read the Electronic Signature, Status Register, CFI,

Block Protection Status, Configuration Register Status or Protection Register. When the

addressed bank is in Read CFI, Read Status Register or Read Electronic Signature mode,

the WAIT signal is asserted during the X-latency, the WAIT state and at the end of a 4, 8 and

16 Word burst. It is only de-asserted when output data are valid.

See Table 24: Synchronous Read AC characteristics, and Figure 11: Synchronous Burst

Read AC waveforms, for details.

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