This Data Sheet may be revised by subsequent versions

©2004 Eon Silicon Solution, Inc., www.essi.com.tw

or modifications due to changes in technical specifications.

7

EN25F05

Rev. B, Issue Date: 2008/06/23

Hold Function

The Hold (HOLD) signal is used to pause any serial communications with the device without reset-

ting the clocking sequence. However, taking this signal Low does not terminate any Write Status

Register, Program or Erase cycle that is currently in progress.

To enter the Hold condition, the device must be selected, with Chip Select (CS#) Low. The Hold

condition starts on the falling edge of the Hold (HOLD) signal, provided that this coincides with Serial

Clock (CLK) being Low (as shown in Figure 4.).

The Hold condition ends on the rising edge of the Hold (HOLD) signal, provided that this coincides

with Serial Clock (CLK) being Low.

If the falling edge does not coincide with Serial Clock (CLK) being Low, the Hold condition starts af-

ter Serial Clock (CLK) next goes Low. Similarly, if the rising edge does not coincide with Serial Clock

(CLK) being Low, the Hold condition ends after Serial Clock (CLK) next goes Low. (This is shown in

Figure 4.).

During the Hold condition, the Serial Data Output (DO) is high impedance, and Serial Data Input (DI)

and Serial Clock (CLK) are Don’t Care.

Normally, the device is kept selected, with Chip Select (CS#) driven Low, for the whole duration of

the Hold condition. This is to ensure that the state of the internal logic remains unchanged from the

moment of entering the Hold condition.

If Chip Select (CS#) goes High while the device is in the Hold condition, this has the effect of

resetting the internal logic of the device. To restart communication with the device, it is necessary to

drive Hold (HOLD) High, and then to drive Chip Select (CS#) Low. This prevents the device from

going back to the Hold condition.

Figure 4. Hold Condition Waveform

INSTRUCTIONS

All instructions, addresses and data are shifted in and out of the device, most significant bit first.

Serial Data Input (DI) is sampled on the first rising edge of Serial Clock (CLK) after Chip Select (CS#)

is driven Low. Then, the one-byte instruction code must be shifted in to the device, most significant

bit first, on Serial Data Input (DI), each bit being latched on the rising edges of Serial Clock (CLK).

The instruction set is listed in Table 4. Every instruction sequence starts with a one-byte instruction

code. Depending on the instruction, this might be followed by address bytes, or by data bytes, or by

both or none. Chip Select (CS#) must be driven High after the last bit of the instruction sequence

has been shifted in. In the case of a Read Data Bytes (READ), Read Data Bytes at Higher Speed

(Fast_Read), Read Status Register (RDSR) or Release from Deep Power-down, and Read Device

ID (RDI) instruction, the shifted-in instruction sequence is followed by a data-out sequence. Chip

Select (CS#) can be driven High after any bit of the data-out sequence is being shifted out.

In the case of a Page Program (PP), Sector Erase (SE), Block Erase (BE), Chip Erase (CE), Write

Status Register (WRSR), Write Enable (WREN), Write Disable (WRDI) or Deep Power-down (DP)

instruction, Chip Select (CS#) must be driven High exactly at a byte boundary, otherwise the

instruction is rejected, and is not executed. That is, Chip Select (CS#) must driven High when the

number of clock pulses after Chip Select (CS#) being driven Low is an exact multiple of eight. For

Page Program, if at any time the input byte is not a full byte, nothing will happen and WEL will not be

reset.