25LC010A データシートの表示（PDF） - Microchip Technology

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25LC010A

1K-4K SPI Serial EEPROM HighTemp Family Data Sheet

Microchip Technology 

2.0 PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 2-1.

TABLE 2-1: PIN FUNCTION TABLE

Name Pin Number

Function

CS

SO

WP

VSS

SI

SCK

HOLD

VCC

1

Chip Select Input

2

Serial Data Output

3

Write-Protect Pin

4

Ground

5

Serial Data Input

6

Serial Clock Input

7

Hold Input

8

Supply Voltage

2.1 Chip Select (CS)

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

deselects the device and forces it into Standby mode.

However, a programming cycle which is already

initiated or in progress will be completed, regardless of

the CS input signal. If CS is brought high during a

program cycle, the device will go into Standby mode as

soon as the programming cycle is complete. When the

device is deselected, SO goes to the high-impedance

state, allowing multiple parts to share the same SPI

bus. A low-to-high transition on CS after a valid write

sequence initiates an internal write cycle. After power-

up, a low level on CS is required prior to any sequence

being initiated.

2.2 Serial Output (SO)

The SO pin is used to transfer data out of the

25LCXXXA. During a read cycle, data is shifted out on

this pin after the falling edge of the serial clock.

2.3 Write-Protect (WP)

The WP pin is a hardware write-protect input pin. When

it is low, all write to the array or STATUS registers are

disabled, but any other operations function normally.

When WP is high, all functions including nonvolatile

writes, operate normally. At any time, when WP is low,

the write enable Reset latch will be reset and program-

ming will be inhibited. However, if a write cycle is

already in progress, WP going low will not change or

disable the write cycle. See Table 5-1 for Write-Protect

Functionality Matrix.

25LCXXXA

2.4 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.

2.5 Serial Clock (SCK)

The SCK is used to synchronize the communication

between a master and the 25LCXXXA. 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.

2.6 Hold (HOLD)

The HOLD pin is used to suspend transmission to the

25LCXXXA while in the middle of a serial sequence

without having to retransmit the entire sequence 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 must be

brought low while SCK is low, otherwise the HOLD

function will not be invoked until the next SCK high-to-

low transition. The 25LCXXXA must remain selected

during this sequence. The SI, SCK and SO pins are in

a high-impedance state during the time the device is

paused and transitions on these pins will be ignored. To

resume serial communication, HOLD must be brought

high while the SCK pin is low, otherwise serial

communication will not resume. Lowering the HOLD

line at any time will tri-state the SO line.

© 2009 Microchip Technology Inc.

Preliminary

DS22136B-page 7

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