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CAT25C32/64

Doc. No. 1001, Rev. G

FUNCTIONAL DESCRIPTION

The CAT25C32/64 supports the SPI bus data

transmission protocol. The synchronous Serial Peripheral

Interface (SPI) helps the CAT25C32/64 to interface

directly with many of today’s popular microcontrollers.

The CAT25C32/64 contains an 8-bit instruction register.

(The instruction set and the operation codes are detailed

in the instruction set table)

After the device is selected with

CS going low, the first

byte will be received. The part is accessed via the SI pin,

with data being clocked in on the rising edge of SCK.

The first byte contains one of the six op-codes that define

the operation to be performed.

PIN DESCRIPTION

SI: Serial Input

SI is the serial data input pin. This pin is used to input all

opcodes, byte addresses, and data to be written to the

25C32/64. Input data is latched on the rising edge of the

serial clock.

SO: Serial Output

SO is the serial data output pin. This pin is used to

transfer data out of the 25C32/64. During a read cycle,

data is shifted out on the falling edge of the serial clock.

SCK: Serial Clock

SCK is the serial clock pin. This pin is used to synchronize

Instruction

Opcode

Operation

WREN

0000 0110

Enable Write Operations

WRDI

0000 0100

Disable Write Operations

RDSR

0000 0101

Read Status Register

WRSR

0000 0001

Write Status Register

READ

0000 0011

Read Data from Memory

WRITE

0000 0010

Write Data to Memory

INSTRUCTION SET

Figure 1. Sychronous Data Timing

Note: Dashed Line= mode (1, 1) — ———

VALID IN

VIL

HI-Z

HI-Z

CS

SCK

SI

SO

tFI

Note:

(1) This parameter is tested initially and after a design or process change that affects the parameter.

Symbol

Parameter

Max.

Units

Power-up to Read Operation

1

ms

Power-up to Write Operation

1

ms