11.2.22 Power-down (B9h)
Although the standby current during normal operation is relatively low, standby current can be
further reduced with the Power-down instruction. The lower power consumption makes the Power-
down instruction especially useful for battery powered applications (See ICC1 and ICC2 in AC
Characteristics). The instruction is initiated by driving the /CS pin low and shifting the instruction
code “B9h” as shown in figure 22.
The /CS pin must be driven high after the eighth bit has been latched, If this is not done the Power-
down instruction will not be executed. After /CS is driven high, the Power-down state will be
entered within the time duration of tDP (See AC Characteristics). While in the Release power-down
/Device ID instruction, which restores the device to normal operation, will be recognized. All other
instructions are ignored. This includes the Read Status Register instruction, which is always
available during normal operation. Ignoring all but one instruction makes the Power Down state a
useful condition for securing maximum write protection. The device always powers-up in the
normal operation with the standby current of ICC1.
Figure 22. Deep Pwer-down Instruction Sequence Diagram
11.2.23 Release Power-down / Device ID (ABh)
The Release from Power-down / Device ID instruction is a multi-purpose instruction. It can be used
to release the device from the power-down state or obtain the device electronic identification (ID)
To release the device from the power-down state, the instruction is issued by driving the /CS pin
low, shifting the instruction code “ABh” and driving /CS high as shown in figure 23a. Release from
power-down will take the time duration of tRES1 (See AC Characteristics) before the device will
resume normal operation and other instructions are accepted. The /CS pin must remain high
during the tRES1 time duration.
When used only to obtain the Device ID while not in the power-down state, instruction is initiated
by driving the /CS pin low and shifting the instruction code “ABh” followed by 3-dummy bytes. The
Device ID bits are then shifted on the falling edge of CLK with most significant bit (MSB) first as
shown in figure 23b. The Device ID value for the FM25Q32 is listed in Manufacturer and Device
Identification table. The Device ID can be read continuously. The instruction is completed by
driving /CS high.
When used to release the device from the power-down state and obtain the Device ID, the