AT49BV040A-70TU Atmel, AT49BV040A-70TU Datasheet - Page 5

• Manufacturer Part Number: AT49BV040A-70TU
• Description: IC FLASH 4MBIT 70NS 32TSOP
• Manufacturer: Atmel

Specifications of AT49BV040A-70TU

• Format - Memory: FLASH
• Memory Type: FLASH
• Memory Size: 4M (512K x 8)
• Speed: 70ns
• Interface: Parallel
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-TSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4.5
4.5.1
4.6
4.7
4.8
4.9
3358C–FLASH–3/05
Boot Block Programming Lockout
Product Identification
DATA Polling
Toggle Bit
Hardware Data Protection
Boot Block Lockout Detection
The device has one designated block that has a programming lockout feature. This feature pre-
vents programming of data in the designated block once the feature has been enabled. The size
of the block is 16K bytes. 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 device is updated. This feature does not have to be activated;
the boot block’s usage as a write protected region is optional to the user. The address range of
the boot block is 00000 to 03FFF.
Once the feature is enabled, the data in the boot block can no longer be erased or programmed.
Data in the main memory block can still be changed through the regular programming method.
To activate the lockout feature, a series of six program commands to specific addresses with
specific data must be performed. Please refer to the
A software method is available to determine if programming of the boot block section is locked
out. When the device is in the software product identification mode (see
tification Entry and Exit”
programming the boot block is locked out. If the data on I/O0 is low, the boot block can be pro-
grammed; if the data on I/O0 is high, the program lockout feature has been activated and the
block cannot be programmed. The software product identification code should be used to return
to standard operation.
The product identification mode identifies the device and manufacturer 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 (for hardware operation) or Software Product Identification.
The manufacturer and device code is the same for both modes.
The AT49BV040A features DATA polling to indicate the end of a program cycle. During a pro-
gram cycle an attempted read of the last byte loaded will result in the complement of the loaded
data on I/O7. Once the program cycle has been completed, true data is valid on all outputs and
the next cycle may begin. DATA polling may begin at any time during the program cycle.
In addition to DATA polling the AT49BV040A provides another method for determining the end
of a program or erase cycle. During a program or erase operation, successive attempts to read
data from the device will result in I/O6 toggling between one and zero. Once the program cycle
has completed, I/O6 will stop toggling and valid data will be read. Examining the toggle bit may
begin at any time during a program cycle.
Hardware features protect against inadvertent programs to the AT49BV040A in the following
ways: (a) V
inhibit: holding any one of OE low, CE high or WE high inhibits program cycles. (c) Noise filter:
pulses of less than 15 ns (typical) on the WE or CE inputs will not initiate a program cycle.
CC
sense: if V
CC
is below 1.8V (typical), the program function is inhibited. (b) Program
sections) a read from address location 00002H will show if
“Command Definition Table” on page
AT49BV040A
“Software Product Iden-
6.
5