M28W640FCT_06 datasheet(13/77 Pages) STMICROELECTRONICS

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M28W640FCT, M28W640FCB

Signal descriptions

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2.7

Reset (RP)

The Reset input provides a hardware reset of the memory. When Reset is at VIL, the

memory is in reset mode: the outputs are high impedance and the current consumption is

minimized. After Reset all blocks are in the Locked state. When Reset is at VIH, the device is

in normal operation. Exiting reset mode the device enters read array mode, but a negative

transition of Chip Enable or a change of the address is required to ensure valid data outputs.

2.8

VDD supply voltage

VDD provides the power supply to the internal core of the memory device. It is the main

power supply for all operations (Read, Program and Erase).

2.9

VDDQ supply voltage

VDDQ provides the power supply to the I/O pins and enables all Outputs to be powered

independently from VDD. VDDQ can be tied to VDD or can use a separate supply.

2.10

VPP Program supply voltage

VPP is both a control input and a power supply pin. The two functions are selected by the

voltage range applied to the pin. The Supply Voltage VDD and the Program Supply Voltage

VPP can be applied in any order.

If VPP is kept in a low voltage range (0V to 3.6V) VPP is seen as a control input. In this case

a voltage lower than VPPLK gives an absolute protection against program or erase, while

VPP > VPP1 enables these functions (see Table 15: DC characteristics, for the relevant

values). VPP is only sampled at the beginning of a program or erase; a change in its value

after the operation has started does not have any effect on Program or Erase, however for

Double or Quadruple Word Program the results are uncertain.

If VPP is in the range 11.4V to 12.6V it acts as a power supply pin. In this condition VPP must

be stable until the Program/Erase algorithm is completed (see Table 17 and Table 18).

2.11

VSS Ground

VSS is the reference for all voltage measurements.

Note: Each device in a system should have VDD, VDDQ and VPP decoupled with a 0.1µF

capacitor close to the pin. See Figure 7: AC measurement load circuit. The PCB track

widths should be sufficient to carry the required VPP program and erase currents.

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