MBM29F040C-55/-70/-90
■ FUNCTIONAL DESCRIPTION
Read Mode
The MBM29F040C 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-tOE time).
Standby Mode
The MBM29F040C has two standby modes, a CMOS standby mode (CE input held at VCC ±0.3 V.), when the
current consumed is less than 5 µA; and a TTL standby mode (CE is held at VIH) when the current required is
reduced to approximately 1 mA. 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. In the
standby mode the outputs are in a high impedance state, independent of the OE input.
If the device is deselected during erasure or programming, the device will draw active current until the operation
is completed.
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 device 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 device outputs by toggling address A0 from VIL to VIH. All
addresses are DON’T CARES except A0, A1, and A6. (Recommend VIL for the other pins.)
The manufacturer and device codes may also be read via the command register, for instances when the
MBM29F040C is erased or programmed in a system without access to high voltage on the A9 pin. The command
sequence is illustrated in Table 5. (Refer to Autoselect Command section.)
Byte 0 (A0 = VIL) represents the manufacture’s code (Fujitsu = 04H) and byte 1 (A0 = VIH) represents the device
identifier code (MBM29F040C = A4H). These two bytes are given in the Table 3. All identifiers for manufactures
and device will exhibit odd parity with the MSB (DQ7) defined as the parity bit. In order to read the proper device
codes when executing the autoselect, A1 must be VIL. (See Table 3.)
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