Device
Operation
READ: The AT49BV162A(T)/163A(T) is accessed like an EPROM. When CE and OE are low
and WE is high, the data stored at the memory location determined by the address pins are
asserted on the outputs. The outputs are put in the high impedance state whenever CE or OE
is high. This dual-line control gives designers flexibility in preventing bus contention.
COMMAND SEQUENCES: When the device is first powered on, it will be reset to the read or
standby mode, depending upon the state of the control line inputs. In order to perform other
device functions, a series of command sequences are entered into the device. The command
sequences are shown in the “Command Definition in Hex” table on page 12 (I/O8 - I/O15 are
don’t care inputs for the command codes). The command sequences are written by applying a
low pulse on the WE or CE input with CE or WE low (respectively) and OE high. The address
is latched on the falling edge of CE or WE, whichever occurs last. The data is latched by the
first rising edge of CE or WE. Standard microprocessor write timings are used. The address
locations used in the command sequences are not affected by entering the command
sequences.
RESET: A RESET input pin is provided to ease some system applications. When RESET is at
a logic high level, the device is in its standard operating mode. A low level on the RESET input
halts the present device operation and puts the outputs of the device in a high impedance
state. When a high level is reasserted on the RESET pin, the device returns to the read or
standby mode, depending upon the state of the control inputs.
ERASURE: Before a byte/word can be reprogrammed, it must be erased. The erased state of
memory bits is a logical “1”. The entire device can be erased by using the Chip Erase com-
mand or individual sectors can be erased by using the Sector Erase command.
CHIP ERASE: The entire device can be erased at one time by using the six-byte chip erase
software code. After the chip erase has been initiated, the device will internally time the erase
operation so that no external clocks are required. The maximum time to erase the chip is tEC
.
If the sector lockdown has been enabled, the chip erase will not erase the data in the sector
that has been locked out; it will erase only the unprotected sectors. After the chip erase, the
device will return to the read or standby mode.
SECTOR ERASE: As an alternative to a full chip erase, the device is organized into 39 sec-
tors (SA0 - SA38) that can be individually erased. The Sector Erase command is a six-bus
cycle operation. The sector address is latched on the falling WE edge of the sixth cycle while
the 30H data input command is latched on the rising edge of WE. The sector erase starts after
the rising edge of WE of the sixth cycle. The erase operation is internally controlled; it will
automatically time to completion. The maximum time to erase a sector is tSEC. When the sec-
tor programming lockdown feature is not enabled, the sector will erase (from the same Sector
Erase command). An attempt to erase a sector that has been protected will result in the oper-
ation terminating immediately.
BYTE/WORD PROGRAMMING: Once a memory block is erased, it is programmed (to a logi-
cal “0”) on a byte-by-byte or on a word-by-word basis. Programming is accomplished via the
internal device command register and is a four-bus cycle operation. The device will automati-
cally generate the required internal program pulses.
4
AT49BV162/163A(T)
3349G–FLASH–7/04
ATMEL [ ATMEL ]
