X25644/46

X25324/26

X25164/66

2

PIN DESCRIPTIONS

Serial Output (SO)

SO is a push/pull serial data output pin. During a read

cycle, data is shifted out on this pin. Data is clocked out by

the falling edge of the serial clock.

Serial Input (SI)

SI is a serial data input pin. All opcodes, byte addresses,

and data to be written to the memory are input on this pin.

Data is latched by the rising edge of the serial clock.

Serial Clock (SCK)

The Serial Clock controls the serial bus timing for data

input and output. Opcodes, addresses, or data present on

the SI pin are latched on the rising edge of the clock input,

while data on the SO pin change after the falling edge of

the clock input.

Chip Select (CS)

When CS is HIGH, the device is deselected and the SO

output pin is at high impedance and unless a nonvolatile

write cycle is underway, the device will be in the standby

power mode. CS LOW enables the device’s, placing it in

the active power mode. It should be noted that after

power-up, a HIGH to LOW transition on CS is required

prior to the start of any operation.

Write Protect (WP)

When WP is low and the nonvolatile bit WPEN is “1”,

nonvolatile writes to the device’s Status Register are

disabled, but the part otherwise functions normally. When

WP is held high, all functions, including nonvolatile writes

to the Status Register operate normally. If an internal

Status Register Write Cycle has already been initiated,

WP going low while WPEN is a “1” will have no effect on

this write. Subsequent write attempts to the Status

Register under these conditions will be disabled.

The WP pin function is blocked when the WPEN bit in the

Status Register is “0”. This allows the user to install the

device in a system with WP pin grounded and still be able

to program the Status Register. The WP pin functions will

be enabled when the WPEN bit is set to a “1”.

Reset (RESET/RESET)

RESET/RESET is an active LOW/HIGH, open drain out-

put which goes active whenever the Watchdog Timer is

enabled and CS remains either HIGH or LOW longer than

the selectable Watchdog time-out period. It will remain

CS will reset the Watchdog Timer.

PIN CONFIGURATION

PIN NAMES

7029 FRM T01

Symbol

Description

CS

Chip Select Input

SO

Serial Output

SI

Serial Input

SCK

Serial Clock Input

WP

Write Protect Input

Ground

Supply Voltage

RESET/RESET

Reset Output

14-LEAD SOIC

X25644/46

NC

CS

CS

SO

WP

VSS

1

2

3

4

5

6

7

RESET/RESET

SCK

SI

NC

14

13

12

11

10

9

8

NC

VCC

VCC

NC

7036 FRM 02

8-LEAD SOIC

X25324/26

CS

WP

SO

1

2

3

4

RESET/RESET

8

7

6

5

VCC

14-LEAD TSSOP

X25324/28

SO

WP

VSS

1

2

3

4

5

6

7

RESET/RESET

SCK

SI

14

13

12

11

10

9

8

NC

VCC

NC

X25164/66

VSS

SCK

SI

CS

NC

NC

NC

NC

X25164/66

0.345”

0.200”

0.197”

0.244”

0.177”

0.244”

Not to Scale