FM25V02 - 256Kb SPI FRAM

Rev. 3.0

Jan. 2012

Page 9 of 17

Sleep Mode

A

low

power

mode

called

Sleep

Mode

is

implemented on the FM25V02 and FM25VN02

device. The device will enter this low power state

when the SLEEP op-code B9h is clocked-in and a

rising edge of /S is applied. Once in sleep mode, the

C and D pins are ignored and Q will be high-Z, but

the device continues to monitor the /S pin. On the

next falling edge of /S, the device will return to

pin remains in a hi-Z state during the wakeup period.

The device will not necessarily respond to an opcode

within the wakeup period.

To start the wakeup

procedure, the controller may send a “dummy” read,

Figure 12. Sleep Mode Entry

Device ID

The FM25V02 and FM25VN02 device can be interrogated for its manufacturer, product identification, and die

revision. The RDID op-code 9Fh allows the user to read the manufacturer ID and product ID, both of which are

read-only bytes. The JEDEC-assigned manufacturer ID places the Ramtron identifier in bank 7, therefore there are

six bytes of the continuation code 7Fh followed by the single byte C2h. There are two bytes of product ID, which

includes a Family code, a Density code, a Sub code, and Product Revision code.

Table 6. Manufacturer and Product ID

Bit

7

6

5

4

3

2

1

0

Hex

Manufacturer ID

0

1

1

1

1

1

1

1

7F

Continuation code

0

1

1

1

1

1

1

1

7F

Continuation code

0

1

1

1

1

1

1

1

7F

Continuation code

0

1

1

1

1

1

1

1

7F

Continuation code

0

1

1

1

1

1

1

1

7F

Continuation code

0

1

1

1

1

1

1

1

7F

Continuation code

1

1

0

0

0

0

1

0

C2

JEDEC assigned Ramtron C2h in bank 7

Family

Density

Hex

Device ID (1

0

0

1

0

0

0

1

0

22h

Density: 01h=128K, 02h=256K, 03h=512K, 04=1M

Sub

Rev.

Rsvd

Device ID (2

0

0

0

0

0

0

0

0

00h

00h=FM25V02, 01h=FM25VN02

Figure 13. Read Device ID

S

C

D

Q

Enter Sleep

Mode

S

C

D

Q

7Fh

…

7Fh

C2h

00h

Six bytes of continuation code 7Fh

9Fh

22h

1

6

. . . . . . .