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ROHM BU9891GUL-W User Guide

Summary

This high-reliability serial EEPROM provides robust non-volatile data storage using a simple 3-line interface method. Featuring low power consumption, up to 2MHz operating speed, and excellent data retention, this memory is ideal for various embedded systems. The comprehensive manual details all electrical specifications, timing characteristics, absolute ratings, and recommended operational conditions (1.7V–5.5V). It is designed for engineers developing general-use electronic equipment such as consumer audio-visual devices, communication gear, or office automation hardware requiring stable memory solutions.

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High Reliability Serial EEPROMs

WL-CSP EEPROM family Microwire Bus

BU9891GUL-W No.10001EAT10

●Description BU9891GUL-W is serial EEPROM of serial 3-line interface method

●Features 1) 3-line communications of chip select, serial clock, serial data input / output (the case where input and output are shared) 2) Actions available at high speed 2MHz clock (2.5~5.5V) 3) Speed write available (write time 5ms max.) 4) 1.7~5.5V single power source action 5) Address auto increment function at read action 6) Write mistake prevention function Write prohibition at power on Write prohibition by command code Write mistake prevention function at low voltage 7) Program cycle auto delete and auto end function 8) Program condition display by READY / BUSY 9) Low current consumption At write action (at 5V): 1.2m A (Typ.) At read action (at 5V): 0.3m A (Typ.) At standby action (at 5V): 0.1μA (Typ.) (CMOS input) 10) Data retention for 40 years 11) Data rewrite up to 100,000 times 12) Data at shipment all addresses FFFFh

Capacity Bit format Type Power source voltage Package type

4Kbit 256×16 BU9891GUL-W 1.7~5.5V VCSP50L1

●Absolute Maximum Ratings(Ta=25℃)

Parameter Symbol Ratings Unit

Impressed voltage VCC -0.3~+6.5 V

Permissible dissipation Pd 220 (VCSP50L1 ) *1 m W

Storage temperature range Tstg -65~+125 ℃

Action temperature range Topr -40~+85 ℃

Terminal voltage ‐ -0.3~VCC+0.3 V * When using at Ta=25℃ or higher, 2.2m W (to be reduced per 1℃.

www.rohm.com 2010.07 - Rev.A

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

Page Summary Contents For ROHM BU9891GUL-W User Guide

Page 1 High Reliability Serial EEPROMs WL-CSP EEPROM family Microwire Bus BU9891GUL-W No.10001EAT10 ●Description BU9891GUL-W is serial EEPROM of serial 3-line interface method ●Features 1) 3-line communicati...
Page 2 BU9891GUL-W Technical Note ●Recommended action conditions Parameter Symbol Ratings Unit Power source voltage VCC 1.7~5.5 Input voltage VIN 0~VCC ●Memory cell characteristics (VCC=1.7~5.5V) Limit Param...
Page 3 BU9891GUL-W Technical Note ●Action timing characteristics (Ta=-40~+85℃, VCC=2.5~5.5V) 2.5V≦VCC≦5.5V Parameter Symbol Unit Min. Typ. Max. SK frequency f SK - - 2 MHz SK “H” time t SKH 230 - - ns SK “L”...
Page 4 BU9891GUL-W Technical Note ●BU9891GUL-W Characteristic data (The following characteristic data are Typ. values.) IL [μ [V IH [V Ta=-40℃ Ta=-40℃ Ta=-40℃ Ta=25℃ Ta=25℃ 0.8 Ta=25℃ Ta=85℃ Ta=85℃ Ta=85℃ SP...
Page 5 BU9891GUL-W Technical Note ● BU9891GUL-W Characteristic data (The following characteristic data are Typ. values.) f S [M z] t D IH [n s] t C [μ s] IC (W IT f SK=500k Hz f SK=500k Hz SPEC DATA=0000h DA...
Page 6 BU9891GUL-W Technical Note ●BU9891GUL-W Characteristic data (The following characteristic data are Typ. values.) Ta=-40℃ Ta=-40℃ Ta=-40℃ Ta=25℃ Ta=25℃ Ta=25℃ Ta=85℃ Ta=85℃ Ta=85℃ SPEC SPEC VCC[V] VCC[...
Page 7 BU9891GUL-W Technical Note ●Block diagram Command decode Power source voltage detection Control Clock generation Write High voltage occurrence prohibition Address Address Command buffer decoder 8bit 8...
Page 8 BU9891GUL-W Technical Note ●Description of operations Communications of the Microwire Bus are carried out by SK (serial clock), DI (serial data input),DO (serial data output) ,and CS (chip select) for...
Page 9 BU9891GUL-W Technical Note ●Timing chart 1) Read cycle (READ) SK 1 2 DI 1 A7 A1 A0 DO 0 D15 D14 D1 D0 D15 D14 High-Z *1 Start bit When data “1” is input for the first time after the rise of CS, this i...
Page 10 BU9891GUL-W Technical Note ●Application 1) Method to cancel each command ○READ Start bit Ope code Address Data 1bit 2bit 8bit 16bit Cancel is available in all areas in read mode. ・Method to cancel:can...
Page 11 BU9891GUL-W Technical Note 3) Equivalent circuit Output circuit Input citcuit RESET int. CS CSint. OEint. Fig.40 Output circuit (DO) Fig.41 Input circuit (CS) Input circuit Input circuit CS int. CS in...
Page 12 BU9891GUL-W Technical Note ○Pull up resistance Rpu and pull down resistance Rpd of DO pin As for pull up and pull down resistance value, select an appropriate value to this resistance value from micro...
Page 13 BU9891GUL-W Technical Note 6) When to directly connect DI and DO This IC has independent input terminal DI and output terminal DO, and separate signals are handled on timing chart, meanwhile, by inser...
Page 14 BU9891GUL-W Technical Note ○Selection of resistance value R The resistance R becomes through current limit resistance at data collision. When through current flows, noises of power source line and ins...
Page 15 BU9891GUL-W Technical Note 7) Notes on power ON/OFF ・At power ON/OFF, set CS “L”. When CS is “H”, this IC gets in input accept status (active). If power is turned on in this status, noises and the lik...
Page 16 BU9891GUL-W Technical Note ●Notes for use (1) Described numeric values and data are design representative values, and the values are not guaranteed. (2) We believe that application circuit examples ar...
Page 17 BU9891GUL-W Technical Note ●Ordering part number Part No. Part No. Package W-CELL Packaging and forming specification GUL : VCSP50L1 E2: Embossed tape and reel VCSP50L1(BU9891GUL-W) <Tape and Reel ...
Page 18 Notice No copying or reproduction of this document, in part or in whole, is permitted without the consent of ROHM Co.,Ltd. The content specified herein is subject to change for improvement without not...

Manual Details

Brand ROHM
Pages 18
File Size 465.04 KB
Published July 10, 2026
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Frequently Asked Questions

What is the recommended operating voltage range for this EEPROM?

The suggested power source voltage (VCC) ranges from 1.7V to 5.5V.

How many times can the data be rewritten in this chip?

The device supports up to 100,000 data rewrite times at Ta=25℃.

What are the typical current consumption rates during operation?

At 5V, standby draw is 0.1μA, write action consumes 1.2mA, and read action consumes 0.3mA.

Is this product suitable for high-reliability or aerospace applications?

No, it is not designed or manufactured for equipment requiring extremely high levels of reliability or direct life support systems.