FM25H20-G Ramtron, FM25H20-G Datasheet - Page 8

• Manufacturer Part Number: FM25H20-G
• Description: EIAJ SOIC8
• Manufacturer: Ramtron

Hold
The /HOLD pin can be used to interrupt a serial
operation without aborting it. If the bus master pulls
the /HOLD pin low while C is low, the current
Sleep Mode
A low power mode called Sleep Mode is
implemented on the FM25H20. The device will enter
this low power state when the SLEEP op-code (B9h)
is clocked in, and the device seeing the rising edge of
/S. Once in sleep mode, the C and D pins are ignored
and Q will go to a hi-Z state, but the device continues
to monitor the /S pin. On the next falling edge of /S,
Rev. 2.2
Sept. 2010
S
C
D
Q
S
C
D
Q
0
0
0
0
0
1
0
1
0
2
0
2
op-c ode
0
3
op-code
0
3
S
C
D
Q
0
4
0
4
0
5
0
5
1
6
1
6
0
7
1
7
M SB
MSB
x
0
x
0
Figure 11. Sleep Mode Entry
x
Figure 10. Memory Read
1
Figure 9. Memory Write
x
1
x
2
x
2
18-bit Address
18-bit Address
x
3
x
3
x
4
x
4
x
x
5
5
17
17
6
operation will pause. Taking the /HOLD pin high
while C is low will resume an operation. The
transitions of /HOLD must occur while C is low, but
the C and /S pins can toggle during a hold state.
6
the device will return to normal operation within t
(450 µs max.). The Q pin remains in a hi-Z state
during the wakeup period. The FM25H20 will not
necessarily respond to an opcode within the wakeup
period. To start the wakeup procedure, the controller
may send a “dummy” read, for example, and wait the
remaining t
3
3
4
4
2
2
5
5
REC
1
1
6
6
time.
Sleep
entry
LSB
LSB MSB
0
0
7
7
MSB
7
0
7
0
FM25H20 - 2Mb SPI FRAM
6
1
6
1
5
2
5
2
D ata
Data
4
3
4
3
3
4
3
4
2
5
2
5
1
6
Page 8 of 15
1
6
LSB
0
LSB
7
0
7
REC