MR20H40VDFR 데이터 시트보기 (PDF) - Extech Instruments Corporation.

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MR20H40VDFR

NVRAM 4Mb 3.3V 512Kx8 SPI

Extech Instruments Corporation. 

Pin Functions

MR20H40 / MR25H40

Figure 3 – DFN Package Pin Diagram (Top View)

CS 1

SO 2

WP 3

VSS

4

8

VDD

7 HOLD

6 SCK

5 SI

Signal

Name

CS

SO

WP

VSS

SI

SCK

HOLD

VDD

Pin I/O

1 Input

2 Output

3 Input

4

Refer-

ence

5 Input

6 Input

7 Input

8 Supply

Table 1 – Pin Functions

Function Description

Chip Select

Serial Output

Write Protect

An active low chip select for the serial MRAM. When chip select is high, the

memory is powered down to minimize standby power, inputs are ignored

and the serial output pin is Hi-Z. Multiple serial memories can share a com-

mon set of data pins by using a unique chip select for each memory.

The data output pin is driven during a read operation and remains Hi-Z at

all other times. SO is Hi-Z when HOLD is low. Data transitions on the data

output occur on the falling edge of SCK.

A low on the write protect input prevents write operations to the Status

Register.

Ground

Power supply ground pin.

Serial Input

Serial Clock

Hold

All data is input to the device through this pin. This pin is sampled on the

rising edge of SCK and ignored at other times. SI can be tied to SO to create

a single bidirectional data bus if desired.

Synchronizes the operation of the MRAM. The clock can operate up to 50

MHz to shift commands, address, and data into the memory. Inputs are

captured on the rising edge of clock. Data outputs from the MRAM occur

on the falling edge of clock. The serial MRAM supports both SPI Mode 0

(CPOL=0, CPHA=0) and Mode 3 (CPOL=1, CPHA=1). In Mode 0, the clock is

normally low. In Mode 3, the clock is normally high. Memory operation is

static so the clock can be stopped at any time.

A low on the Hold pin interrupts a memory operation for another task.

When HOLD is low, the current operation is suspended. The device will

ignore transitions on the CS and SCK when HOLD is low. All transitions of

HOLD must occur while CS is low.

Power Supply Power supply voltage from +3.0 to +3.6 volts.

Copyright © Everspin Technologies 2014

6

MR20H40 / MR25H40 Revision 11, 8/2014

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