BR93G56-3B Datasheet, PDF (20/40 Pages) Rohm – MicroWire BUS EEPROM (3-Wire)

BR93G56-3B
Datasheet
(a) Pull Up Resistance R_PU and Pull Down Resistance R_PD of DO pin
As for pull up and pull down resistance value, select an appropriate resistor value from microcontroller V_IH, V_IL,
and V_OH, I_OH, V_OL, I_OL characteristics of this IC.
Microcontroller
VILM
Rpu
Low input
EEPROM
IOLE
VOLE
Low output
Figure 46. DO Pull Up Resistance
Rpu ≧ ^{Vcc－VOLE}
I_OLE
・・・③
V_OLE ≦ V_ILM
・・・④
Example) When Vcc =5V, V_OLE=0.4V, I_OLE=2.1mA, V_ILM=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, V_OLE becomes
0.4V or below, and with V_ILM(=0.8V), the equation ④ is also satisfied.
・V_OLE
・I_OLE
・V_ILM
: EEPROM V_OL specifications
: EEPROM I_OL specifications
: Microcontroller V_IL specifications
Microcontroller
VIHM
High input
Rpd
EEPROM
VOHE
IOHE _{High output}
Figure 47. DO Pull Down Resistance
Rpd ≧
V_OHE ≧
V_OHE
I_OHE
V_IHM
・・・⑤
・・・⑥
Example) When Vcc =5V, V_OHE=Vcc－0.2V, I_OHE=0.1mA,
V_IHM=Vcc×0.7V from the equation ⑤,
5－0.2
Rpd ≧ _0.1×10-3
∴
Rpd ≧ 48 [kΩ]
With the value of Rpd to satisfy the above equation, V_OHE becomes 2.4V
or below, and with V_IHM (=3.5V), the equation ⑥ is also satisfied.
・V_OHE
・I_OHE
・V_IHM
: EEPROM V_OH specifications
: EEPROM I_OH specifications
: Microcontroller V_IH specifications
(b) READY / BUSY STATUS Display (DO terminal)
This display outputs the internal STATUS signal. When CS is started after t_CS
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 t_E/W, and during this period, other command is not accepted.
R/B display = high (READY) = command wait STATUS
（DO STATUS） _{After tE/W (Max5ms) the following command is accepted.}
Therefore, CS=high in the period of t_E/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 active. 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
t_SV
BUSY
t_E/W
READY
Figure 48. READY/BUSY STATUS Output Timing Chart
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