GD25LQ16xIGx 1.8V Uniform Sector Dual and Quad Serial Flash
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4. DEVICE OPERATION
SPI Mode
Standard SPI
The GD25LQ16 feature a serial peripheral interface on 4 signals bus: Serial Clock (SCLK), Chip Select (CS#),
Serial Data Input (SI) and Serial Data Output (SO). Both SPI bus mode 0 and 3 are supported. Input data is
latched on the rising edge of SCLK and data shifts out on the falling edge of SCLK.
Dual SPI
The GD25LQ16 supports Dual SPI operation when using the “Dual Output Fast Read” and “Dual I/O Fast
Read” (3BH and BBH) commands. These commands allow data to be transferred to or from the device at two
times the rate of the standard SPI. When using the Dual SPI command the SI and SO pins become bidirectional
I/O pins: IO0 and IO1.
Quad SPI
The GD25LQ16 supports Quad SPI operation when using the “Quad Output Fast Read”, “Quad I/O Fast
Read”, “Quad I/O Word Fast Read” (6BH, EBH, E7H) commands. These commands allow data to be transferred
to or from the device at four times the rate of the standard SPI. When using the Quad SPI command the SI and
SO pins become bidirectional I/O pins: IO0 and IO1, and WP# and HOLD# pins become IO2 and IO3. Quad
SPI commands require the non-volatile Quad Enable bit (QE) in Status Register to be set.
QPI
The GD25LQ16 supports Quad Peripheral Interface (QPI) operations only when the device is switched
ftom Standard/Dual/Quad SPI mode to QPI mode using the “Enable the QPI (38H)” command. The QPI
mode utilizes all four IO pins to input the command code. Standard/Dual/Quad SPI mode and QPI mode are
exclusive. Only one mode can be active at any given times. “Enable the QPI (38H)” and “Disable the QPI (FFH)”
commands are used to switch between these two modes. Upon power-up and after software reset using “Reset
(99H)” command, the default state of the device is Standard/Dual/Quad SPI mode. The QPI mode requires the
non-volatile Quad Enable bit (QE) in Status Register to be set.
Hold
The HOLD# signal goes low to stop any serial communications with the device, but doesn’t stop the operation
of write status register, programming, or erasing in progress.
The operation of HOLD, need CS# keep low, and starts on falling edge of the HOLD# signal, with SCLK
signal being low (if SCLK is not being low, HOLD operation will not start until SCLK being low). The HOLD
condition ends on rising edge of HOLD# signal with SCLK being low (If SCLK is not being low, HOLD
operation will not end until SCLK being low).
The SO is high impedance, both SI and SCLK don’t care during the HOLD operation, if CS# drives high
during HOLD operation, it will reset the internal logic of the device. To re-start communication with chip, the
HOLD# must be at high and then CS# must be at low.
Rev.1.0
59 - 7
ELM [ ELM ELECTRONICS ]
