MBM29F400TC-55/-70-90/MBM29F400BC-55/-70-90
■ FUNCTIONAL DESCRIPTION
Read Mode
The MBM29F400TC/BC has two control functions which must be satisfied in order to obtain data at the outputs.
CE is the power control and should be used for a device selection. OE is the output control and should be used
to gate data to the output pins if a device is selected.
Address access time (tACC) is equal to the delay from stable addresses to valid output data. The chip enable
access time (tCE) is the delay from stable addresses and stable CE to valid data at the output pins. The output
enable access time is the delay from the falling edge of OE to valid data at the output pins (Assuming the
addresses have been stable for at least tACC - tCE time).
Standby Mode
There are two ways to implement the standby mode on the MBM29F400TC/BC devices, one using both the CE
and RESET pins; the other via the RESET pin only.
When using both pins, a CMOS standby mode is achieved with CE and RESET inputs both held at VCC ± 0.3 V.
Under this condition the current consumed is less than 5 µA max. A TTL standby mode is achieved with CE and
RESET pins held at VIH. Under this condition the current is reduced to approximately 1mA. During Embedded
Algorithm operation, VCC Active current (ICC2) is required even CE = VIH. The device can be read with standard
access time (tCE) from either of these standby modes.
When using the RESET pin only, a CMOS standby mode is achieved with RESET input held at VSS ± 0.3 V
(CE = “H” or “L”). Under this condition the current is consumed is less than 5 µA max. A TTL standby mode is
achieved with RESET pin held at VIL, (CE= “H” or “L”). Under this condition the current required is reduced to
approximately 1mA. Once the RESET pin is taken high, the device requires tRH of wake up time before outputs
are valid for read access.
In the standby mode the outputs are in the high impedance state, independent of the OE input.
Output Disable
With the OE input at a logic high level (VIH), output from the device is disabled. This will cause the output pins
to be in a high impedance state.
Autoselect
The autoselect mode allows the reading out of a binary code from the device and will identify its manufacturer
and type. This mode is intended for use by programming equipment for the purpose of automatically matching
the devices to be programmed with its corresponding programming algorithm. This mode is functional over the
entire temperature range of the device.
To activate this mode, the programming equipment must force VID (11.5 V to 12.5 V) on address pin A9. Two
identifier bytes may then be sequenced from the devices outputs by toggling address A0 from VIL to VIH. All
addresses are don't cares except A0, A1 and A6 ( A-1) (See “MBM29F400TC/BC Sector Protection Verify
Autoselect Codes” in ■DEVICE BUS OPERATION).
The manufacturer and device codes may also be read via the command register, for instances when the
MBM29F400TC/BC is erased or programmed in a system without access to high voltage on the A9 pin. The
command sequence is illustrated in “MBM29F400TC/BC Command Definitions” in ■DEVICE BUS OPERATION
(refer to Autoselect Command section).
A0 =VIL representsthemanufacturer’scode(Fujitsu=04h)andA0 =VIH thedeviceidentifiercode(MBM29F400TC
= 23h and MBM29F400BC = ABh for ×8 mode; MBM29F400TC = 2223h and MBM29F400BC = 22ABh for ×16
mode). These two bytes/words are given in “MBM29F400TC/BC Sector Protection Verify Autoselect Codes” and
“Expanded Autoselect Code Table” in ■DEVICE BUS OPERATION. All identifiers for manufacturer and device
will exhibit odd parity with DQ7 defined as the parity bit. In order to read the proper device codes when executing
the autoselect, A1 must be VIL (See “MBM29F400TC/BC Sector Protection Verify Autoselect Codes” and
“Expanded Autoselect Code Table” in ■DEVICE BUS OPERATION).
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