BR93A76-WM Ver la hoja de datos (PDF) - ROHM Semiconductor

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BR93A76-WM

High Reliability Series EEPROMs Microwire BUS

ROHM Semiconductor 

BR93L□□-W Series, 93A□□-WM Series, BR93H□□-WC Series

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 microcontroller

VIH, VIL, and VOH, IOH, VOL, IOL characteristics of this IC.

Microcontroller

Rpu

VILM

“L” input

EEPROM

IOLE

VOLE

“L” output

Rpu

Vcc－VOLE

≧

IOLE

VOLE ≦ VILM

・・・③

・・・④

Example) When VCC =5V, VOLE=0.4V, IOLE=2.1mA, VILM=0.8V,

from the equation ③,

5－0.4

Rpu ≧ 2.1×10-3

∴

Rpu ≧ 2.2 [kΩ]

Fig.77 DO pull up resistance

With the value of Rpu to satisfy the above equation, VOLE becomes 0.4V

or below, and with VILM(=0.8V), the equation ④ is also satisfied.

・VOLE

・IOLE

・VILM

: EEPROM VOL specifications

: EEPROM IOL specifications

: Microcontroller VIL specifications

Microcontroller

VIHM

“H” input Rpd

EEPROM

VOHE

IOHE “H” output

VOHE

Rpd ≧ IOHE

VOHE ≧ VIHM

・・・⑤

・・・⑥

Example) When VCC =5V, VOHE=Vcc－0.2V, IOHE=0.1mA,

VIHM=Vcc×0.7V from the equation ⑤,

5－0.2

Rpd ≧ 0.1×10-3

∴

Rpd ≧ 48 [kΩ]

Fig.78 DO pull down resistance

With the value of Rpd to satisfy the above equation, VOHE becomes 2.4V

or below, and with VIHM (=3.5V), the equation ⑥ is also satisfied.

・VOHE

・IOHE

・VIHM

: EEPROM VOH specifications

: EEPROM IOH specifications

: Microcontroller VIH specifications

5) READY / BUSY status display (DO terminal)

(common to BR93L46-W/A46-WM,BR93L56-W/A56-WM, BR93L66-W/A66-WM, BR93L76-W/A76-WM, BR93L86-W/A86-WM)

This display outputs the internal status signal. When CS is started after tCS (Min.200ns)

from CS fall after write command input, “H” or “L” is output.

R/B display＝“L” (BUSY) = write under execution

（DO status） After the timer circuit in the IC works and creates the period of tE/W, this time circuit completes automatically.

And write to the memory cell is made in the period of tE/W, and during this period, other command is not accepted.

R/B display = “H” (READY) = command wait status

（DO status） Even after tE/W (max.5ms) from write of the memory cell, the following command is accepted.

Therefore, CS=“H” in the period of tE/W, and when input is in SK, DI, malfunction may occur, therefore, DI=“L” in the area

CS=“H”. (Especially, in the case of shared input port, attention is required.)

*Do not input any command while status signal is output. Command input in BUSY area is cancelled, but command input in READY area is accepted.

Therefore, status READY output is cancelled, and malfunction and mistake write may be made.

CS

STATUS

SK

CLOCK

DI

WRITE

INSTRUCTION

DO High-Z

tSV

READY

BUSY

Fig.79 R/B status output timing chart

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© 2011 ROHM Co., Ltd. All rights reserved.

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2011.02 - Rev.F

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