23A1024 datasheet(12/32 Pages) MICROCHIP

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23A1024/23LC1024

DS25142A-page 12

Preliminary

 2011 Microchip Technology Inc.

3.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 3-1.

TABLE 3-1:

PIN FUNCTION TABLE

3.1

Chip Select (CS)

A low level on this pin selects the device. A high level

deselects the device and forces it into Standby mode.

When the device is deselected, SO goes to the high-

impedance state, allowing multiple parts to share the

same SPI bus. After power-up, a low level on CS is

required, prior to any sequence being initiated.

3.2

Serial Output (SO)

The SO pin is used to transfer data out of the 23A1024/

23LC1024. During a read cycle, data is shifted out on

this pin after the falling edge of the serial clock.

3.3

Serial Input (SI)

The SI pin is used to transfer data into the device. It

receives instructions, addresses, and data. Data is

latched on the rising edge of the serial clock.

3.4

Serial Dual Interface Pins(SIO0,

SIO1)

The SIO0 and SIO1 pins are used for SDI mode of

operation. Functionality of these I/O pins is shared with

SO and SI.

3.5

Serial Quad Interface Pins (SIO0 –

SIO3)

The SIO0 through SIO3 pins are used for SQI mode of

operation. Because of the shared functionality of these

pins the HOLD feature is not available when using SQI

mode.

3.6

Serial Clock (SCK)

The SCK is used to synchronize the communication

between a master and the 23A1024/23LC1024.

Instructions, addresses or data present on the SI pin

are latched on the rising edge of the clock input, while

data on the SO pin is updated after the falling edge of

the clock input.

3.7

Hold Function (HOLD)

The HOLD pin is used to suspend transmission to the

23A1024/23LC1024 while in the middle of a serial

sequence without having to re-transmit the entire

sequence over again. It must be held high any time

this function is not being used. Once the device is

selected and a serial sequence is underway, the

HOLD pin may be pulled low to pause further serial

communication without resetting the serial sequence.

The HOLD pin should be brought low while SCK is

low, otherwise the HOLD function will not be invoked

until the next SCK high-to-low transition. The

23A1024/23LC1024 must remain selected during this

sequence. The SI and SCK levels are “don’t cares”

during the time the device is paused and any

transitions on these pins will be ignored. To resume

serial communication, HOLD should be brought high

while the SCK pin is low, otherwise serial

communication will not be resumed until the next SCK

high-to-low transition.

The SO line will tri-state immediately upon a high-to

low transition of the HOLD pin, and will begin

outputting again immediately upon a subsequent low-

to-high transition of the HOLD pin, independent of the

state of SCK.

Hold functionality is not available when operating in

SQI mode.

Name

SOIC/

PDIP

TSSOP

Function

Chip Select Input

SO/SIO1

Serial Data Output/SDI/SQI

SIO2

SQI Pin

VSS

4Ground

SI/SIO0

Serial Data Input/SDI/SQI Pin

SCK

Serial Clock Input

HOLD/SIO3

Hold/SQI Pin

VCC

Power Supply

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