SA25F005LEM8 Просмотр технического описания (PDF) - Saifun Semiconductors

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SA25F005LEM8

512Kb Serial Flash with 25MHz SPI Bus Interface

Saifun Semiconductors 

Chip Select (CSb)

The SA25F005 is selected when the CSb

pin is low. When the device is not selected,

data is not accepted via the SI pin, and the

SO pin remains in a high impedance state.

Hold Condition

The HOLDb pin is used in conjunction with

the CSb pin to select the SA25F005. When

the device is selected and a serial

sequence is underway, HOLDb can be

used to pause the serial communication

with the master device without resetting the

serial sequence.

To enter the hold condition the device must

be selected, with CSb low.

SA25F005 Advanced Information

SAIFUN

15

As shown in Figure 8, the Hold condition

starts on the falling edge of the HOLDb

signal, provided that SCK is low. The Hold

condition ends on the rising edge of the

HOLDb signal, provided that SCK is low. If

the falling edge does not coincide with SCK

being low, the Hold condition starts only

after SCK next goes low. Similarly, if the

rising edge does not coincide with SCK

being low, the Hold condition ends only

after SCK next goes low.

During the Hold condition, SO is high

impedance, and SI and SCK are Don’t

Care. In most cases, the device is kept

selected, with CSb driven low, for the entire

duration of the Hold condition, which

ensures that the internal logic state

remains unchanged from the moment it

enters the Hold condition.

NOTE:

Driving CSb high while HOLDb is still

low is not a legal operation.

SCK

HOLD

Hold

Condition

(Standard Use)

Hold

Condition

(Non-Standard Use)

Figure 8. Hold Condition

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