FM24V01 - 128Kb I2C FRAM
Sleep Mode
A low power mode called Sleep Mode is
implemented on the FM24V01 device. The device
will enter this low power state when the Sleep
command 86h is clocked-in. Sleep Mode entry can be
entered as follows:
1.
2.
3.
The master sends a START command.
The master sends Reserved Slave ID 0xF8
The master sends the I
2
C-bus slave address of
the slave device it needs to identify. The last
bit is a ‘Don’t care’ value (R/W bit). Only one
device must acknowledge this byte (the one
that has the I
2
C-bus slave address).
The master sends a Re-START command.
5.
6.
7.
The master sends Reserved Slave ID 0x86
The FM24V01 sends an ACK.
The master sends STOP to ensure the device
enters sleep mode.
Once in sleep mode, the device draws I
ZZ
current, but
the device continues to monitor the I
2
C pins. Once
the master sends a Slave Address that the FM24V01
identifies, it will “wakeup” and be ready for normal
operation within t
REC
(400
s
max.). As an alternative
method of determining when the device is ready, the
master can send read or write commands and look for
an ACK. While the device is waking up, it will
NACK the master until it is ready.
4.
Start
By Master
S
Rsvd Slave ID (F8)
Address
Start
Address
Stop
A
Slave Address
X A
S
Rsvd Slave ID (86)
A
P
By FM24V01
Acknowledge
Figure 12. Sleep Mode Entry
Rev. 1.1
Sept. 2011
Page 8 of 14
RAMTRON [ RAMTRON INTERNATIONAL CORPORATION ]
