AM29F040 データシートの表示（PDF） - Advanced Micro Devices

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AM29F040

4 Megabit (524,288 x 8-Bit) CMOS 5.0 Volt-only, Sector Erase Flash Memory

Advanced Micro Devices 

Table 1. Am29F040 User Bus Operations

Operation

CE OE WE A0

A1

A6

A9

I/O

Autoselect Manufacturer Code (Note 1)

Autoselect Device Code (Note 1)

Read (Note 4)

L

L

H

L

L

L

VID

Code

L

L

H

H

L

L

VID

Code

L

L

H

A0

A1

A6

A9

RD

Standby

H

X

X

X

X

X

X

HIGH Z

Output Disable

L

H

H

X

X

X

X

HIGH Z

Write

L

H

L

A0

A1

A6

A9 PD (Note 2)

Verify Sector Protect (Note 3)

L

L

H

L

H

L

VID

Code

Autoselect Device Unprotect Code

L

L

H

H

H

L

VID

Code

Legend:

L = Logic 0, H = Logic 1, X = Don’t Care. See DC Characteristics for voltage levels.

Notes:

1. Manufacturer and device codes may also be accessed via a command register write sequence. Refer to Tables 2 and 4.

2. Refer to Table 3 for valid PD (Program Data) during a write operation.

3. Refer to the section on Sector Protection.

4. WE can be VIL if OE is VIL, OE at VIH initiates the write operations.

Read Mode

The Am29F040 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 device selec-

tion. 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 en-

able 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 Am29F040 has two standby modes, a CMOS

standby mode (CE input held at VCC ± 0.5 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. 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 program-

ming, 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 pro-

gramming 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.

The manufacturer and device codes may also be read

via the command register, for instances when the

Am29F040 is erased or programmed in a system with-

out access to high voltage on the A9 pin. The command

sequence is illustrated in Table 4 (refer to Autoselect

Command section).

Byte 0 (A0 = VIL) represents the manufacturer’s code

(AMD = 01H) and byte 1 (A0 = VIH) the device identifier

code (Am29F040 = A4H). All identifiers for manufac-

turer and device exhibit odd parity with the MSB (DQ7)

defined as the parity bit. See Table 2.

Am29F040

7

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