FM1808B – 256Kb Bytewide 5V F-RAM
A(14:0)
CE
Address
Latch &
Decoder
A(14:0)
32,768 x 8 FRAM Array
Control
WE
Logic
OE
I/O Latch
Bus Driver
DQ(7:0)
Figure 1. Block Diagram
Pin Description
Pin Name
A(14:0)
DQ(7:0)
/CE
/OE
/WE
VDD
VSS
Type
Input
I/O
Input
Input
Input
Supply
Supply
Description
Address: The 15 address lines select one of 32,768 bytes in the F-RAM array. The
address value is latched on the falling edge of /CE.
Data: 8-bit bi-directional data bus for accessing the F-RAM array.
Chip Enable: /CE selects the device when low. Asserting /CE low causes the
address to be latched internally. Address changes that occur after /CE goes low
will be ignored until the next falling edge occurs.
Output Enable: Asserting /OE low causes the FM1808B to drive the data bus when
valid data is available. Deasserting /OE high causes the DQ pins to be tri-stated.
Write Enable: Asserting /WE low causes the FM1808B to write the contents of the
data bus to the address location latched by the falling edge of /CE.
Supply Voltage: 5V
Ground
Functional Truth Table
/CE
/WE
Function
H
X
Standby/Precharge
X
Latch Address (and Begin Write if /WE=low)
L
H
Read
L
Write
Note: The /OE pin controls only the DQ output buffers.
Document Number: 001-86209 Rev. **
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