BS640HD8V datasheet(16/89 Pages) AMD

16 / 89 page

Am29BDS128H/Am29BDS640H

27024B3 May 10, 2006

D A TA

SH EE T

ICC2 in the “DC Characteristics” section on page 54

represents the active current specification for the write

mode. The AC Characteristics section contains timing

specification tables and timing diagrams for write oper-

ations.

Accelerated Program Operation

The device offers accelerated program operations

through the ACC function. ACC is primarily intended to

allow faster manufacturing throughput at the factory.

If the system asserts VHH on this input, the device auto-

matically enters the aforementioned Unlock Bypass

mode and uses the higher voltage on the input to

reduce the time required for program operations. The

system would use a two-cycle program command

sequence as required by the Unlock Bypass mode.

Removing VHH from the ACC input returns the device

to nor mal operation. Note that sectors must be

unlocked prior to raising ACC to VHH. Note that the

ACC pin must not be at VHH for operations other than

accelerated programming, or device damage may

result. In addition, the ACC pin must not be left floating

or unconnected; inconsistent behavior of the device

may result.

When at VIL, ACC locks all sectors. ACC should be at

VIH for all other conditions.

Autoselect Mode

The autoselect mode provides manufacturer and de-

vice identification, and sector protection verification,

through identifier codes output from the internal regis-

ter (which is separate from the memory array) on

DQ15–DQ0. This mode is primarily intended for pro-

gramming equipment to automatically match a device

to be programmed with its corresponding program-

ming algorithm. However, the autoselect codes can

also be accessed in-system through the command

When using programming equipment, the autoselect

mode requires VID on address pin A9. Address pins

must be as shown in Table 3, “Autoselect Codes (High

Voltage Method),” on page 15. In addition, when verify-

ing sector protection, the sector address must appear

on the appropriate highest order address bits (see

Table 4, “Am29BDS128H Boot Sector/Sector Block

Addresses for Protection/Unprotection,” on page 16).

Table 3 shows the remaining address bits that are

don’t care. When all necessary bits have been set as

required, the programming equipment may then read

the corresponding identifier code on DQ15–DQ0.

However, the autoselect codes can also be accessed

in-system through the command register, for instances

when the device is erased or programmed in a system

without access to high voltage on the A9 pin. The com-

mand sequence is illustrated in Table 20, “Memory

Array Command Definitions,” on page 46. Note that if a

Bank Address (BA) is asserted during the third write

cycle of the autoselect command, the host system can

read autoselect data that bank and then immediately

read array data from the other bank, without exiting the

autoselect mode.

To access the autoselect codes in-system, the host

system can issue the autoselect command via the

command register, as shown in Table 20, “Memory

Array Command Definitions,” on page 46. This method

does not require VID. Autoselect mode may only be en-

tered and used when in the asynchronous read mode.

Refer to the “Autoselect Command Sequence” section

on page 36 for more information.

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