BR93G86-3_15 Datasheet, PDF (20/40 Pages) Rohm – MicroWire BUS EEPROM (3-Wire)

BR93G86-3
○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
VILM
Rpu
low input
EEPROM
IOLE
VOLE
low output
Figure 46. DO pull up resistance
Microcontroller
VIHM
high input Rpd
EEPROM
VOHE
IOHE _{high output}
Figure 47. DO pull down resistance
Rpu ≧^{VCC－VOLE}
IOLE
・・・③
VOLE ≦ VILM
・・・④
Example) When VCC =5V, VOLE=0.4V, IOLE=2.1mA, VILM=0.8V,
from the equation ③,
Rpu
≧ ^5－0.4
2.1×10^-3
∴
Rpu ≧ 2.2 [kΩ]
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
Rpd ≧
VOHE
IOHE
VOHE ≧ VIHM
・・・⑤
・・・⑥
Example) When VCC =5V, VOHE=VCC－0.2V, IOHE=0.1mA,
VIHM=VCC×0.7V from the equation ⑤,
Rpd ≧
5－0.2
0.1×10^-3
∴
Rpd ≧ 48 [kΩ]
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
○READY / BUSY STATUS display (DO terminal)
This display outputs the internal STATUS signal. When CS is started after tCS
from CS fall after write command input, high or low is output.
R/B display＝low (BUSY) = write under execution
（DO STATUS） _{After the timer circuit in the IC works and creates the period of tE/W, this timer circuit completes automatically.}
And the memory cell is written in the period of tE/W, and during this period, other command is not accepted.
R/B display = high (READY) = command wait STATUS
（DO STATUS） _{After tE/W (max.5ms) the following command is accepted.}
Therefore, CS=high in the period of tE/W, and If signals are input in SK, DI, malfunction may occur,
therefore, DI=low in the area
CS=high. (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 occur.
CS
SK
CLOCK
DI
WRITE
INSTRUCTION
DO High-Z
STATUS
tSV
BUSY
tE/W
READY
Figure 48. READY/BUSY STATUS output timing chart
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21.DEC.2015 REV.002