AT25SF321 datasheet(34/48 Pages) DIALOG

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AT25SF321

DS-25SF321–047F–8/2017

11.4 Resume from Deep Power-Down (ABh)

In order to exit the Deep Power-Down mode and resume normal device operation, the Resume from Deep Power-Down

command must be issued. The Resume from Deep Power-Down command is the only command that the device will

recognize while in the Deep Power-Down mode.

To resume from the Deep Power-Down mode, the CS pin must first be asserted and the opcode of ABh must be clocked

into the device. Any additional data clocked into the device after the opcode will be ignored. When the CS pin is

deasserted, the device will exit the Deep Power-Down mode within the maximum time of tRDPD and return to the standby

mode. After the device has returned to the standby mode, normal command operations such as Read Array can be

resumed.

If the complete opcode is not clocked in before the CS pin is deasserted, or if the CS pin is not deasserted on an byte

boundary (multiples of eight bits), then the device will abort the operation and return to the Deep Power-Down mode.

Figure 11-4. Resume from Deep Power-Down

11.4.1 Resume from Deep Power-Down and Read Device ID (ABh)

The Resume from Deep Power-Down command can also be used to read the Device ID.

When used to release the device from the Power-Down state and obtain the Device ID, the CS pin must first be asserted

and opcode of ABh must be clocked into the device, followed by 3 dummy bytes. The Device ID bits are then shifted out

on the falling edge of SCLK with most significant bit (MSB) first as shown in Figure 11-4. This command only outputs a

single byte Device ID. The Device ID value for the AT25SF321 is listed in Table 11-1.

After the last bit (bit 0) of the Device ID has been clocked out, the sequence will repeat itself starting again with bit 7 as

long as the CS pin remains asserted and the SCK pin is being pulsed. After CS is deasserted it must remain high for a

time duration of tRDPO before new commands can be received.

The same instruction may be used to read device ID when not in power down. In that case, /CS does not have to remain

high remain after it is deasserted.

MSB

10101011

OPCODE

GH-

MPEDANCE

DeepPower

DownModeCur

ent

Act

veCur

ent

andbyModeCur

ent

RDPD

AT25SF321 Datasheet(PDF) 34 Page - Dialog Semiconductor