45PE80 View Datasheet(PDF) - Micron Technology

Part Name

Description

Manufacturer

45PE80

Micron Serial NOR Flash Memory

Micron Technology 

75MHz, Serial Peripheral Interface Flash Memory

Serial Peripheral Interface Modes

Serial Peripheral Interface Modes

The device can be driven by a microcontroller while its serial peripheral interface is in

either of the two modes shown in the following table. The difference between the two

modes is the clock polarity when the bus master is in standby mode and not transfer-

ring data. Input data is latched in on the rising edge of the clock, and output data is

available from the falling edge of the clock.

Table 4: SPI Modes

Note 1 applies to the entire table

SPI Modes

CPOL = 0, CPHA = 0

CPOL = 1, CPHA = 1

Clock Polarity

C remains at 0 for (CPOL = 0, CPHA = 0)

C remains at 1 for (CPOL = 1, CPHA = 1)

Note: 1. The listed SPI modes are supported in extended, dual, and quad SPI protocols.

The following figures show an example of three memory devices in extended SPI proto-

col in a simple connection to an MCU on a SPI bus. Because only one device is selected

at a time, that one device drives DQ1, while the other devices are High-Z.

Resistors ensure that the device is not selected if the bus master leaves chip select (S#)

High-Z. The bus master might enter a state in which all input/output is High-Z simulta-

neously, such as when the bus master is reset. Therefore, the serial clock must be con-

nected to an external pull-down resistor so that S# is pulled HIGH while the serial clock

is pulled LOW. This ensures that S# and the serial clock are not HIGH simultaneously

and that tSHCH is met. The typical resistor value of 100kΩ, assuming that the time con-

stant R × Cp (Cp = parasitic capacitance of the bus line), is shorter than the time the bus

master leaves the SPI bus in High-Z.

Example: Cp = 50 pF, that is R × Cp = 5μs. The application must ensure that the bus

master never leaves the SPI bus High-Z for a time period shorter than 5μs. W# and

HOLD# should be driven either HIGH or LOW, as appropriate.

PDF: 09005aef845660e5

m45pe80.pdf - Rev. C 03/14 EN

13

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© 2011 Micron Technology, Inc. All rights reserved.

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