Xicor X76F200 Technical data

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ISO 7816 Compatible
2K

X76F200

Secure SerialFlash

FEATURES

• 64-bit Password Security

• One Array (240 Bytes) Two Pass w ords (16 Bytes)
—Read Password
—Write Password

• Programmable Passwords

• Retry Counter Register
—Allows 8 tries before clearing of the array

• 32-bit Response to Reset (RST Input)

• 8 byte Sector Write mode

• 1MHz Clock Rate

• 2 wire Serial Interface

• Low Power CMOS
—2.0 to 5.5V operation
—Standby current Less than 1µA
—Active current less than 3 mA

• High Reliability Endurance:
—100,000 Write Cycles

• Data Retention: 100 years

• Available in:
—8 lead PDIP, SOIC, TSSOP, Smart Card and

Smart Card Module

256 x 8 bit

DESCRIPTION

The X76F200 is a Pass word Access Security Supervisor,
containing one 1920-bit Secure SerialFlash array.
Access to the memory array can be controlled by two
64-bit passwords. These passwords protect read and
write operations of the memory array .

The X76F200 features a serial interface and software
protocol allowing operation on a popular two wire bus.
The bus signals are a clock Input (SCL) and a
bidirectional data input and output (SDA).

The X76F200 also features a synchronous response to
reset providing an automatic output of a hard-wired 32-bit
data stream conforming to the industry standard for
memory cards.

The X76F200 utilizes Xicor’s proprietary Direct Write
cell, providing a minimum endurance of 100,000 cycles
and a minimum data retention of 100 years.

TM

Functional Diagram

CS

SCL

SCL

SDA

SDA

RST

RST

Xicor, Inc. 1999 Patents Pending

9900-5004.3 1/26/99 EP

INTERFACE

Interface

LOGIC

Logic

CHIP ENABLE
DATA T RANSF ER

Data Transfer

ARRAY ACCESS

Array Access

ENABLE

Enable

PASSWORD ARRAY

Password Array

AND PASSWORD

and Password

VERIFICATION LOGIC

Verification Logic

RESET

ISO Reset

RESPONSE REGISTER

Response Register

1

Retry Counter

8K BYTE

SerialFlash ARRAY

Erase Logic

(PASSWORD PROTECTED)

(PASSWORD PROTECTED)

Characteristics subject to change without notice

ARRAY 0

240 Byte

SerialFlash ARRAY

EEPROM Array

RETRY COUNTER

32 BYTE

ARRAY 1

7025 FM 01

X76F200

PIN DESCRIPTIONS
Serial Clock (SCL)

The SCL input is used to clock all data into and out of the
device.

Serial Data (SDA)

SDA is an open drain serial data input/output pin. During
a read cycle, data is shifted out on this pin. During a write
cycle, data is shifted in on this pin. In all other cases, this
pin is in a high impedance state.

Reset (RST)

RST is a device reset pin. When RST is pulsed high the
X76F200 will output 32 bits of fixed data which conforms
to the standard for “synchronous response to reset”. The
part must not be in a write cycle for the response to reset
to occur. See Figure 7. If there is power interrupted
during the Response to Reset, the response to reset will
be aborted and the par t will return to the standby state.
The response to reset is "mask programmable" only!

DEVICE OPERATION

The X76F200 memory array consists of thirty 8-byte
sectors. Read or write access to the array always begins
at the first address of the sector. Read operations then
can continue indefinitely. Write operations must total 8
bytes.

There are two primary modes of operation for the
X76F200; Protected READ and protected WRITE.
Protected operations must be performed with one of two
8-byte passwords .

The basic method of communication for the device is
generating a start condition, then transmitting a
command, followed b y the correct pass word. All parts will
be shipped from the factory with all passwords equal to
‘0’. The user must perform ACK Polling to determine the
validity of the password, before starting a data transfer
(see Acknowledge Polling.) Only after the correct
password is accepted and a ACK polling has been
performed, can the data transfer occur .

To ensure the correct communication, RST must remain
LOW under all conditions except when running a
“Response to Reset sequence”.

Data is transferred in 8-bit segments, with each transfer
being followed by an ACK, generated by the receiving
device.

the nonvolatile write cycle the write operation will be
terminated and the part will reset and enter into a
standby mode.

The basic sequence is illustrated in Figure 1.

PIN NAMES

Symbol Description

SDA Serial Data Input/Output
SCL Serial Clock Input
RST Reset Input
Vcc Supply Voltage
Vss Ground
NC No Connect

PIN CONFIGURATION

PDIP

V

CC

NC
NC

Vss

V

SS

NC
SDA
NC

V

CC

NC
NC

V

SS

1
2

3
4

SOIC

1
2

3
4

TSSOP

1
2

3
4

RST

8

SCL

7

SDA

6

NC

5

Smart Card Module

V

8

CC

RST

7

SCL

6

NC

5

RST

8

SCL

7

SDA

6

NC

5

V

CC

RST

SCL

NC

GND

NC

SDA

NC

After each transaction is completed, the X76F200 will
reset and enter into a standby mode. This will also be the
response if an unsuccessful attempt is made to access a
protected array.

If the X76F200 is in a nonvolatile write cycle a “no ACK”
(SDA=High) response will be issued in response to
loading of the command byte. If a stop is issued prior to

2

X76F200

Figure 1. X76F200 Device Operation

LOAD COMMAND/ADDRESS BYTE

LOAD 8-BYTE

PASSWORD

VERIFY PASSWORD

ACCEPTANCE BY

USE OF ACK POLLING

READ/WRITE

DATA

BYTES

Retry Counter

The X76F200 contains a retry counter. The retry counter
allows 8 accesses with an invalid password before any
action is taken. The counter will increment with any
combination of incorrect passwords. If the retr y counter
overflows, the memory area and both of the passwords
are cleared to "0". If a correct password is received prior
to retry counter overflow, the retry counter is reset and
access is granted.

Device Protocol

The X76F200 supports a bidirectional bus oriented
protocol. The protocol defines any device that sends data
onto the bus as a transmitter and the receiving device as
a receiver. The device controlling the transfer is a master
and the device being controlled is the slave. The master
will always initiate data transf ers and pro vide the clock f or
both transmit and receive operations. Therefore, the
X76F200 will be considered a slave in all applications.

Start Condition

All commands are preceeded by the start condition,
which is a HIGH to LOW transition of SDA when SCL is
HIGH. The X76F200 continuously monitors the SDA and
SCL lines for the start condition and will not respond to
any command until this condition is met.

A start may be issued to terminate the input of a control
byte or the input data to be written. This will reset the
device and leave it ready to begin a new read or write
command. Because of the push/pull output, a start
cannot be generated while the part is outputting data.
Starts are inhibited while a write is in progress.

Stop Condition

All communications must be terminated by a stop
condition. The stop condition is a LOW to HIGH tr ansition
of SDA when SCL is HIGH. The stop condition is also
used to reset the device during a command or data input
sequence and will leave the device in the standby power
mode. As with starts, stops are inhibited when outputting
data and while a write is in progress.

Acknowledge

Acknowledge is a software convention used to indicate
successful data transfer. The transmitting device, either
master or slave, will release the bus after transmitting
eight bits. During the ninth clock cycle the receiver will
pull the SDA line LOW to acknowledge that it received
the eight bits of data.

The X76F200 will respond with an acknowledge after
recognition of a start condition and its slave address. If
both the device and a write condition have been
selected, the X76F200 will respond with an acknowledge
after the receipt of each subsequent eight-bit word.

Clock and Data Conventions

Data states on the SDA line can change only during SCL
LOW. SDA changes during SCL HIGH are reserved for
indicating start and stop conditions. Refer to Figure 2 and
Figure 3.

3

X76F200

Figure 2. Data Validity

SCL

SDA

Data Stable

Data

Change

Figure 3. Definition of Start and Stop Conditions

SCL

SDA

Start Condition Stop Condition

Table 1. X76F200 Instruction Set

Command

after Start

1 0 S

1 0 S

Command Description

S

S

S

S

4

3

2

S

S

4

3

2

0 Sector Write Write

1

0

S

S

1 Sector Read Read

1

0

Password

used

1 1 1 1 1 1 0 0 Change Write Password Write
1 1 1 1 1 1 1 0 Change Read Password Write
0 1 0 1 0 1 0 1 Password ACK Command None

Illegal command codes will be disregarded. The par t will respond with a “no-ACK” to the illegal byte and then return to
the standby mode. All write/read operations require a pass word.

PROGRAM OPERATIONS
Sector Write

The sector write mode requires issuing the 8-bit write
command followed by the password and then the data
bytes transferred as illustrated in figure 4. The write
command byte contains the address of the sector to be
written. Data is written starting at the first address of a
sector and eight bytes must be transferred. After the last
byte to be transferred is acknowledged a stop condition is

issued which starts the nonvolatile write cycle. If more or
less than 8 bytes are transferred, the data in the sector
remains unchanged.

ACK Polling

Once a stop condition is issued to indicate the end of the
host’s write sequence, the X76F200 initiates the internal
nonvolatile write cycle. In order to take advantage of the
typical 5ms write cycle, ACK polling can begin
immediately. This involves issuing the start condition

4

X76F200

follow ed by the new command code of 8 bits (1st byte of
the protocol.) If the X76F200 is still busy with the
nonvolatile write operation, it will issue a “no-ACK” in
response. If the nonvolatile write operation has
completed, an “ACK” will be retur ned and the host can
then proceed with the rest of the protocol.

Data ACK Polling Sequence

WRITE SEQUENCE

COMPLETED

ENTER ACK POLLING

ISSUE START

Password ACK Polling Sequence

PASSWORD LOAD

COMPLETED

ENTER ACK POLLING

ISSUE START

ISSUE

PASSWORD

ACK COMMAND

ISSUE NEW

COMMAND

CODE

ACK

RETURNED?

YES

PROCEED

NO

After the password sequence, there is always a
nonvolatile write cycle. This is done to discourage
random guesses of the password if the device is being
tampered with. In order to continue the transaction, the
X76F200 requires the master to perform a password
ACK polling sequence with the specific command code
of 55h. As with regular Acknowledge polling the user can
either time out for 10ms, and then issue the ACK polling
once, or continuously loop as described in the flow .

If the password that was inserted was correct, then an
“ACK” will be returned once the nonvolatile cycle in
response to the passwrod ACK polling sequence is o ver .

ACK

RETURNED?

YES

PROCEED

NO

READ OPERATIONS

Read operations are initiated in the same manner as
write operations but with a different command code.

Sector Read

With sector read, a sector address is supplied with the
read command. Once the password has been
acknowledged data may be read from the sector. An
acknowledge must follow each 8-bit data transfer. A read
operation always begins at the first byte in the sector, but
may stop at any time. Random accesses to the array are
not possible. Continuous reading from the array will
return data from successive sectors. After reading the
last sector in the array, the address is automatically set to
the first sector in the array and data can continue to be
read out. After the last bit has been read, a stop condition
is generated without sending a preceding acknowledge.

If the password that was inserted was incorrect, then a
“no ACK” will be returned even if the nonvolatile cycle is
over. Therefore, the user cannot be certain that the pass­word is incorrect until the 10ms write cycle time has
elapsed.

5