Technical Note

11/18

www.rohm.com

2010.10 - Rev.A

© 2010 ROHM Co., Ltd. All rights reserved.

BU9832GUL-W

●

At standby

○

Current at standby

Set CS “H”, and be sure to set SCK, SI, WP , HOLD input “L” or “H”. Do not input intermediate electric potantial.

○

Timing

As shown in Fig.41, at standby, when SCK is “H”, even if CS is fallen, SI status is not read at fall edge. SI status is read

at SCK rise edge after fall of CS . At standby and at power ON/OFF, set CS “H” status.

●

WP cancel valid area

WP

is normally fixed to “H” or “L” for use, but when WP is controlled so as to cancel write status register command and

write command, pay attention to the following WP valid timing.

While write or write status register command is executed, by setting WP = “L” in cancel valid area, command can be

cancelled. The area from command ope code before CS rise at internal automatic write start becomes the cancel valid

area. However, once write is started, any input cannot be cancelled. WP input becomes Don’t Care, and cancellation

becomes invalid.

Fig.42

WP

valid timing (WRSR)

Fig.43

WP

valid timing (WRITE)

●

HOLD pin

By HOLD pin, command communication can be stopped temporarily (HOLD status). The HOLD pin carries out command

communications normally when it is HIGH. To get in HOLD status, at command communication, when SCK=LOW, set the

HOLD pin LOW. At HOLD status, SCK and SI become Don’t Care, and SO becomes high impedance (High-Z). To release

the HOLD status, set the HOLD pin HIGH when SCK=LOW. After that, communication can be restarted from the point

before the HOLD status. For example, when HOLD status is made after A5 address input at read, after release of HOLD

status, by starting A4 address input, read can be restarted. When in HOLD status, leave CS LOW. When it is set

CS =HIGH in HOLD status, the IC is reset, therefore communication after that cannot be restarted.

0

1

2

Command start here. SI is read.

Even if CS

―――

is fallen at SCK=SI=”H”,

SI status is not read at that edge.

CS

―――

SCK

SI

Fig.41 Operating timing

15

16

Ope Code

Data

tE/W

Data write time

W P cancel invalid area

SCK

CS

W P cancel invalid area

O pe C ode

Da ta

tE /W

D a ta wr ite tim e

Ad d res s

WP cancel invalid area

WP cancel invalid area