AT49F516-90VC 查看數據表（PDF） - Atmel Corporation
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AT49F516-90VC Datasheet PDF : 13 Pages
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To allow for simple in-system reprogrammability, the
AT49F516 does not require high input voltages for pro-
gramming. Five-volt-only commands determine the read
and programming operation of the device. Reading data
out of the device is similar to reading from an EPROM.
Reprogramming the AT49F516 is performed by erasing a
block of data (entire chip or main memory block) and then
programming on a word by word basis. The typical word
programming time is a fast 10 µs. The end of a program
cycle can be optionally detected by the DATA polling fea-
ture. Once the end of a byte program cycle has been
detected, a new access for a read or program can begin.
The typical number of program and erase cycles is in
excess of 10,000 cycles.
The optional 8K words boot block section includes a repro-
gramming write lock out feature to provide data integrity.
The boot sector is designed to contain user secure code,
and when the feature is enabled, the boot sector is perma-
nently protected from being erased or reprogrammed.
Block Diagram
VCC
GND
OE
WE
CE
ADDRESS
INPUTS
OE, CE, AND WE
LOGIC
Y DECODER
X DECODER
DATA INPUTS/OUTPUTS
I/O15 - I/O0
16
DATA LATCH
INPUT/OUTPUT
BUFFERS
Y-GATING
MAIN MEMORY
(24K WORDS)
OPTIONAL BOOT
BLOCK (8K WORDS)
7FFFH
2000H
1FFFH
0000H
Device Operation
READ: The AT49F516 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 is
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 conten-
tion.
CHIP ERASE: When the boot block programming lockout
feature is not enabled, the boot block and the main memory
block will erase together from the same chip erase com-
mand (See command definitions table). If the boot block
lockout function has been enabled, data in the boot section
will not be erased. However, data in the main memory sec-
tion will be erased. After a chip erase, the device will return
to the read mode.
MAIN MEMORY ERASE: As an alternative to the chip
erase, a main memory block erase can be performed which
will erase all bytes not located in the boot block region to an
FFH. Data located in the boot region will not be changed
during a main memory block erase. The Main Memory
Erase command is a six bus cycle operation. The address
(5555H) is latched on the falling edge of the sixth cycle
while the 30H data input is latched on the rising edge of
WE. The main memory erase starts after the rising edge of
WE of the sixth cycle. Please see Main Memory Erase
cycle waveforms. The Main Memory Erase operation is
internally controlled; it will automatically time to completion.
WORD PROGRAMMING: Once the memory array is
erased, the device is programmed (to a logical “0”) on a
word-by-word basis. Please note that a data “0” cannot be
programmed back to a “1”; only erase operations can con-
vert “0”s to “1”s. Programming is accomplished via the
internal device command register and is a 4 bus cycle
operation (please refer to the Command Definitions table).
The device will automatically generate the required internal
program pulses.
The program cycle has addresses latched on the falling
edge of WE or CE, whichever occurs last, and the data
latched on the rising edge of WE or CE, whichever occurs
first. Programming is completed after the specified tBP cycle
time. The DATA polling feature may also be used to indicate
the end of a program cycle.
BOOT BLOCK PROGRAMMING LOCKOUT: The device
has one designated block that has a programming lockout
feature. This feature prevents programming of data in the
designated block once the feature has been enabled. The
size of the block is 8K words. This block, referred to as the
boot block, can contain secure code that is used to bring up
the system. Enabling the lockout feature will allow the boot
code to stay in the device while data in the rest of the
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AT49F516
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