EN25F40A
OPERATING FEATURES
Standard SPI Modes
The EN25F40A is accessed through a SPI compatible bus consisting of four signals: Serial Clock (CLK),
Chip Select (CS#), Serial Data Input (DI) and Serial Data Output (DO). Both SPI bus operation Modes 0
(0,0) and 3 (1,1) are supported. The primary difference between Mode 0 and Mode 3, as shown in
Figure 3, concerns the normal state of the CLK signal when the SPI bus master is in standby and data is
not being transferred to the Serial Flash. For Mode 0 the CLK signal is normally low. For Mode 3 the
CLK signal is normally high. In either case data input on the DI pin is sampled on the rising edge of the
CLK. Data output on the DO pin is clocked out on the falling edge of CLK.
Figure 3. SPI Modes
Dual SPI Instruction
The EN25F40A supports Dual SPI operation when using the “Dual Output Fast Read and Dual I/O Fast
Read “ (3Bh and BBh) instructions. These instructions allow data to be transferred to or from the Serial
Flash memory at two to three times the rate possible with the standard SPI. The Dual Read instructions
are ideal for quickly downloading code from Flash to RAM upon power-up (code-shadowing) or for
application that cache code-segments to RAM for execution. The Dual output feature simply allows the
SPI input pin to also serve as an output during this instruction. When using Dual SPI instructions the DI
and DO pins become bidirectional I/O pins; DQ0 and DQ1. All other operations use the standard SPI
interface with single output signal.
This Data Sheet may be revised by subsequent versions
or modifications due to changes in technical specifications.
Elite Semiconductor Memory Technology Inc.
6
Rev. D, Issue Date: 2017/02/13
ESMT [ ELITE SEMICONDUCTOR MEMORY TECHNOLOGY INC. ]
