MBM29F400TC datasheet(20/48 Pages) SPANSION

20 / 48 page

MBM29F400TC-55/-70-90/MBM29F400BC-55/-70-90

DQ2

Toggle Bit II

This toggle bit II, along with DQ6, can be used to determine whether the device is in the Embedded Erase

Algorithm or in Erase Suspend.

Successive reads from the erasing sector will cause DQ2 to toggle during the Embedded Erase Algorithm. If the

device is in the erase-suspended-read mode, successive reads from the erase-suspended sector will cause DQ2

to toggle. When the device is in the erase-suspended-program mode, successive reads from the byte address

of the non-erase suspended sector will indicate a logic “1” at the DQ2 bit.

DQ6 is different from DQ2 in that DQ6 toggles only when the standard program or Erase, or Erase Suspend

Program operation is in progress. The behavior of these two status bits, along with that of DQ7, is summarized

as follows:

*1 : These status flags apply when outputs are read from a sector that has been erase-suspended.

*2 : These status flags apply when outputs are read from the byte address of the non-erase suspended sector.

For example, DQ2 and DQ6 can be used together to determine the erase-suspend-read mode (DQ2 toggles while

DQ6 does not). See also “Hardware Sequence Flags” and “Toggle Bit Algorithm” in sFLOW CHART.

Furthermore, DQ2 can also be used to determine which sector is being erased. When the device is in the erase

mode, DQ2 toggles if this bit is read from the erasing sector.

RY/BY

Ready/Busy

The MBM29F400TC/BC provides a RY/BY open-drain output pin as a way to indicate to the host system that

the EmbeddedTM Algorithms are either in progress or completed. If the output is low, the device is busy with

either a program or erase operation. If the output is high, the device is ready to accept any read/write or erase

operation. When the RY/BY pin is low, the device will not accept any additional program or erase commands. If

the MBM29F400TC/BC is placed in an Erase Suspend mode, the RY/BY output will be high. Also, since this is

an open drain output, many RY/BY pins can be tied together in parallel with a pull up resistor to VCC.

During programming, the RY/BY pin is driven low after the rising edge of the fourth write pulse. During an erase

operation, the RY/BY pin is driven low after the rising edge of the sixth write pulse. The RY/BY pin will indicate

a busy condition during the RESET pulse. Refer to “RY/BY Timing Diagram during Program/Erase Operations”

and “RESET/RY/BY Timing Diagram” in sTIMING DIAGRAM for a detailed timing diagram.

Since this is an open-drain output, several RY/BY pins can be tied together in parallel with a pull-up resistor to VCC.

Mode

DQ7

DQ6

DQ2

Program

DQ7

toggles

Erase

toggles

Erase Suspend Read

(Erase-Suspended Sector)*1

toggles

Erase Suspend Program

DQ7*2

toggles

1*2

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