GD25Q41 Datasheet, PDF (33/46 Pages) ELM Electronics – Uniform Sector Dual and Quad Serial Flash

GD25Q41BxIGx Uniform Sector Dual and Quad Serial Flash
7.25. Read Identification (RDID) (9FH)
http://www.elm-tech.com
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. Any 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
Figure30. 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.
Figure 30. Read Identification ID Sequence Diagram
CS#
SCLK
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
SI
SO
CS#
SCLK
9FH
Manufacturer ID
76543210
MSB
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
SI
Memory Type ID15-ID8
Capacity ID7-ID0
SO
7654321076543210
MSB
MSB
7.26. 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 fC1 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 Figure31. 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 deep power down state.
46 - 33
Rev.1.1