X25320

2

PIN NAMES

SYMBOL

DESCRIPTION

CS

Chip Select Input

SO

Serial Output

SI

Serial Input

SCK

Serial Clock Input

WP

Write Protect Input

Ground

Supply Voltage

HOLD

Hold Input

NC

No Connect

3063 PGM T01

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 the 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 X25320 is deselected and the SO

output pin is at high impedance and unless an internal

write operation is underway, the X25320 will be in the

standby power mode.

CS LOW enables the X25320,

placing it in the active power mode. It should be noted

that after power-on, 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 X25320 status register are

disabled, but the part otherwise functions normally.

When

WP is held HIGH, all functions, including nonvola-

tile writes operate normally.

WP going LOW while CS is

still LOW will interrupt a write to the X25320 status

register. If the internal write cycle has already been

initiated,

WP going LOW will have no effect on a write.

The

WP pin function is blocked when the WPEN bit in

the status register is “0”. This allows the user to install the

X25320 in a system with

WP pin grounded and still be

able to write to the status register. The

WP pin functions

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

Hold (

HOLD)

HOLD is used in conjunction with the CS pin to select the

device. Once the part is selected and a serial sequence

is underway,

HOLD may be used to pause the serial

communication with the controller without resetting the

serial sequence. To pause,

HOLD must be brought

LOW while SCK is LOW. To resume communication,

HOLD is brought HIGH, again while SCK is LOW. If the

pause feature is not used,

HOLD should be held HIGH

at all times.

PIN CONFIGURATION

DIP/SOIC

TSSOP

X25320

X25320

3063 ILL F02.2

CS

SO

WP

VSS

1

2

3

4

8

7

6

5

VCC

HOLD

SCK

SI

CS

SO

NC

NC

NC

WP

VSS

1

2

3

4

5

6

7

VCC

HOLD

NC

NC

NC

SCK

SI

14

13

12

11

10

9

8