X25650

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 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 X25650 is deselected and the

SO output pin is at high impedance and unless an

internal write operation is underway, the X25650 will be

in the standby power mode. CS LOW enables the

X25650, 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 X25650 status register are

disabled, but the part otherwise functions normally.

When WP is held HIGH, all functions, including

nonvolatile writes operate normally. WP going LOW

while CS is still LOW will interrupt a write to the

X25650 status register. If the internal write cycle has

already been initiated, WP going LOW will have no

affect 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 X25650 in a system with WP pin grounded and still

be able to write to the status register. The WP pin func-

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

Hold (HOLD)

HOLD is used in conjunction with the CS pin to pause

the device. Once the part is selected and a serial

sequence is underway, HOLD may be used to pause

7037 FRM F02

CS

SO

WP

VSS

1

2

3

4

8

7

6

5

VCC

HOLD

SCK

SI

SOIC

X25650

NC

CS

SO

SO

NC

NC

WP

VSS

NC

NC

NC

VCC

HOLD

HOLD

NC

NC

SCK

SI

NC

NC

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

TSSOP

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

X25650

NOT TO SCALE

0.197"

Max

0.300"

Max

0.252"

0.244"

* Pin 2 and Pin 3 are internally connected. Only one CS needs to

be connected externally.

PIN NAMES

7037 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

HOLD

Hold Input

NC

No Connect

PIN CONFIGURATION