IS93C46-3 Datasheet, PDF (3/10 Pages) Integrated Silicon Solution, Inc – 1,024-BIT SERIAL ELECTRICALLY ERASABLE PROM

IS93C46-3
ISSI ^®
powers up in the write disabled state. The device then
remains in a write disabled state until a WEN instruction
is executed. Thereafter, the device remains enabled until
a WDS instruction is executed or until Vcc is removed.
(NOTE: Neither the WEN nor the WDS instruction has any
effect on the READ instruction.) (See Figure 4.)
Write (WRITE)
The WRITE instruction includes 16 bits of data to be
written into the specified register. After the last data bit
has been applied to DIN, and before the next rising edge of
SK, CS must be brought LOW. The falling edge of CS
initiates the self-timed programming cycle.
After a minimum wait of 250 ns (5V operation) from the
falling edge of CS (tCS), if CS is brought HIGH, DOUT will
indicate the READY/BUSY status of the chip: logical “0”
means programming is still in progress; logical “1” means
the selected register has been written, and the part is
ready for another instruction (see Figure 5). (NOTE: The
combination of CS HIGH, DIN HIGH and the rising edge of
the SK clock, resets the READY/BUSY flag. Therefore, it
is important if you want to access the READY/BUSY flag
, not to reset it through this combination of control
signals.) Before a WRITE instruction can be executed, the
device must be write enabled (see WEN).
Write All (WRALL)
The write all (WRALL) instruction programs all registers
with the data pattern specified in the instruction. While the
WRALL instruction is being loaded, the address field
becomes a sequence of “Don’t Care” bits (see Figure 6).
As with the WRITE instruction, if CS is brought HIGH after
a minimum wait of 250 ns (tCS), the DOUT pin indicates the
READY/BUSY status of the chip (see Figure 6).
Write Disable (WDS)
The write disable (WDS) instruction disables all programming
capabilities. This protects the entire part against acciden-
tal modification of data until a WEN instruction is exe-
cuted. (When Vcc is applied, this part powers up in the
write disabled state.) To protect data, a WDS instruction
should be executed upon completion of each programming
operation. (NOTE: Neither the WEN nor the WDS instruction
has any effect on the READ instruction.) (See Figure 7.)
Erase Register (ERASE)
After the erase instruction is entered, CS must be brought
LOW. The falling edge of CS initiates the self-timed
internal programming cycle. Bringing CS HIGH after a
minimum of tCS, will cause DOUT to indicate the READ/BUSY
status of the chip: a logical “0” indicates programming is
still in progress; a logical “1” indicates the erase cycle is
complete and the part is ready for another instruction (see
Figure 8).
Erase All (ERAL)
Full chip erase is provided for ease of programming.
Erasing the entire chip involves setting all bits in the entire
memory array to a logical “1” (see Figure 9).
INSTRUCTION SET
Instruction
Start Bit
OP Code
Address
READ
1
10
(A5-A0)
WEN
(Write Enable)
1
00
11XXXX
WRITE
1
01
(A5-A0)
WRALL
1
(Write All Registers)
00
01XXXX
WDS
1
00
00XXXX
(Write Disable)
ERASE
1
11
(A5-A0)
ERAL
1
(Erase All Registers)
00
10XXXX
Note: 1. If input data is not 16 bits exactly, the last 16 bits will be taken as input data (a word).
Input Data
D15-D0⁽¹⁾
D15-D0⁽¹⁾
Integrated Silicon Solution, Inc. — 1-800-379-4774
3
Rev. G
04/26/01