W39F010 Datasheet, PDF (7/33 Pages) Winbond – 128K × 8 CMOS FLASH MEMORY

W39F010
6. FUNCTIONAL DESCRIPTION
6.1 Device Bus Operation
6.1.1 Read Mode
The read operation of the W39F010 is controlled by #CE and #OE, both of which have to be low for
the host to obtain data from the outputs. #CE is used for device selection. When #CE is high, the chip
is de-selected and only standby power will be consumed. #OE is the output control and is used to gate
data from the output pins. The data bus is in high impedance state when either #CE or #OE is high.
Refer to the timing waveforms for further details.
6.1.2 Write Mode
Device erasure and programming are accomplished via the command register. The contents of the
register serve as inputs to the internal state machine. The state machine outputs dictate the function
of the device.
The command register itself does not occupy any addressable memory location. The register is a latch
used to store the commands, along with the address and data information needed to execute the
command. The command register is written to bring #WE to logic low state, while #CE is at logic low
state and #OE is at logic high state. Addresses are latched on the falling edge of #WE or #CE,
whichever happens later; while data is latched on the rising edge of #WE or #CE, whichever happens
first. Standard microprocessor write timings are used.
Refer to AC Write Characteristics and the Erase/Programming Waveforms for specific timing
parameters.
6.1.3 Standby Mode
There are two ways to implement the standby mode on the W39F010 device, both using the #CE pin.
A CMOS standby mode is achieved with the #CE input held at VDD ±0.5V. Under this condition the current
is typically reduced to less than 50 μA. A TTL standby mode is achieved with the #CE pin held at VIH.
Under this condition the current is typically reduced to 2 mA.
In the standby mode the outputs are in the high impedance state, independent of the #OE input.
6.1.4 Output Disable Mode
With the #OE input at a logic high level (VIH), output from the device is disabled. This will cause the
output pins to be in a high impedance state.
6.2 Data Protection
The W39F010 is designed to offer protection against accidental erasure or programming caused by
spurious system level signals that may exist during power transitions. During power up the device
automatically resets the internal state machine in the Read mode. Also, with its control register
architecture, alteration of the memory contents only occurs after successful completion of specific
multi-bus cycle command sequences. The device also incorporates several features to prevent
inadvertent write cycles resulting from VDD power-up and power-down transitions or system noise.
Publication Release Date: December 26, 2005
-7-
Revision A4