GD25VQ40CSIG datasheet(32/56 Pages) GIGADEVICE

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Uniform Sector

Dual and Quad Serial Flash

GD25VQ40C

7.23.

Read Identification (RDID) (9FH)

The Read Identification (RDID) command allows the 8-bit manufacturer identification to be read, followed by two bytes

of device identification. The device identification indicates the memory type in the first byte, and the memory capacity of the

device in the second byte. The Read Identification (RDID) command while an Erase or Program cycle is in progress is not

decoded, and has no effect on the cycle that is in progress. The Read Identification (RDID) command should not be issued

while the device is in Deep Power-Down Mode.

The device is first selected by driving CS# to low. Then, the 8-bit command code for the command is shifted in. This

is followed by the 24-bit device identification, stored in the memory, being shifted out on Serial Data Output, each bit being

shifted out during the falling edge of Serial Clock. The command sequence is shown in Figure 28. The Read Identification

(RDID) command is terminated by driving CS# to high at any time during data output. When CS# is driven high, the device

is put in the Standby Mode. Once in the Standby Mode, the device waits to be selected, so that it can receive, decode and

execute commands.

Figure28. Read Identification ID Sequence Diagram

7.24.

High Performance Mode (HPM) (A3H)

The High Performance Mode (HPM) command must be executed prior to Dual or Quad I/O commands when

operating at high frequencies (see fR and fC2 in AC Electrical Characteristics). This command allows pre-charging of

internal charge pumps so the voltages required for accessing the flash memory array are readily available. The

command sequence: CS# goes lowSending A3H command Sending 3-dummy byteCS# goes high. See Figure29.

After the HPM command is executed, the device will maintain a slightly higher standby current (Icc8) than standard SPI

operation. The Release from Power-Down or HPM command (ABH) can be used to return to standard SPI standby

current (Icc1). In addition, Power-Down command (B9H) will also release the device from HPM mode back to standard

SPI standby state.

CS#

SCLK

9 10

MSB

18 19 20 21

22 23

26 27 28 29

30 31

Capacity

JDID7-JDID0

CS#

SCLK

MSB

Memory Type

JDID15-JDID8

11 12 13 14 15

9FH

Manufacturer ID

MSB

Command

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