8

AT49BV/LV320(T)/321(T)

1494H–FLASH–01/03

PRODUCT IDENTIFICATION: The product identification mode identifies the device and man-

ufacturer as Atmel. It may be accessed by hardware or software operation. The hardware

operation mode can be used by an external programmer to identify the correct programming

algorithm for the Atmel product.

For details, see “Operating Modes” on page 18 (for hardware operation) or “Software Product

Identification Entry/Exit” sections on page 25. The manufacturer and device codes are the

same for both modes.

128-BIT PROTECTION REGISTER: The AT49BV/LV32X(T) contains a 128-bit register that

can be used for security purposes in system design. The protection register is divided into two

64-bit blocks. The two blocks are designated as block A and block B. The data in block A is

non-changeable and is programmed at the factory with a unique number. The data in block B

is programmed by the user and can be locked out such that data in the block cannot be repro-

grammed. To program block B in the protection register, the four-bus cycle Program

Protection Register command must be used as shown in the “Command Definition in Hex”

table on page 12. To lock out block B, the four-bus cycle Lock Protection Register command

must be used as shown in the “Command Definition in Hex” table. Data bit D1 must be zero

during the fourth bus cycle. All other data bits during the fourth bus cycle are don’t cares. To

determine whether block B is locked out, the Product ID Entry command is given followed by a

read operation from address 80H. If data bit D1 is zero, block B is locked. If data bit D1 is one,

block B can be reprogrammed. Please see the “Protection Register Addressing Table” on

page 13 for the address locations in the protection register. To read the protection register, the

Product ID Entry command is given followed by a normal read operation from an address

within the protection register. After determining whether block B is protected or not, or reading

the protection register, the Product ID Exit command must be given prior to performing any

other operation.

RDY/BUSY: For the AT49BV/LV321(T), an open-drain READY/BUSY output pin provides

another method of detecting the end of a program or erase operation. RDY/BUSY is actively

pulled low during the internal program and erase cycles and is released at the completion of

the cycle. The open-drain connection allows for OR-tying of several devices to the same

RDY/BUSY line. Please see “Status Bit Table” on page 11 for more details.

HARDWARE DATA PROTECTION: The Hardware Data Protection feature protects against

gramming. (c) Program inhibit: holding any one of OE low, CE high or WE high inhibits

program cycles. (d) Noise filter: pulses of less than 15 ns (typical) on the WE or CE inputs will

INPUT LEVELS: While operating with a 2.65V to 3.6V power supply, the address inputs and

control inputs (OE,CE and WE) may be driven from 0 to 5.5V without adversely affecting the

(for minimum power).