BR93H66-2C Datasheet, PDF (18/32 Pages) Rohm – Serial EEPROM Series Automotive EEPROM 125 Operation Microwire BUS EEPROM

BR93H66-2C
Datasheet
(a) 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
V_IH, V_IL, and V_OH, I_OH, V_OL, I_OL characteristics of this IC.
Microcontroller
VILM
Rpu
EEPROM
IOLE
VOLE
V_cc－V_OLE
Rpu ≧ _IOLE
V_OLE ≦ V_ILM
・・・③
・・・④
Example) When V_CC =5V, V_OLE=0.4V, I_OLE=2.1mA, V_ILM=0.8V,
from the equation ③,
“L” input
Rpu
≧
5－0.4
2.1×10^-3
“L” output
・V_OLE
・I_OLE
・V_ILM
Figure 42. DO Pull up Resistance
∴
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 : EEPROM V_OL specifications
・I_OLE : EEPROM I_OL specifications
・V_ILM : Microcontroller V_IL specifications
Microcontroller
VIHM
“H” input _Rpd
EEPROM
VOHE
IOHE _{“H” output}
Figure 43. DO Pull down Resistance
Rpd ≧ ^VOHE
I_OHE
V_OHE ≧ V_IHM
・・・⑤
・・・⑥
Example) When V_CC =5V, V_OHE=4.8V, I_OHE=0.1mA,
V_IHM=3.5V 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, V_OHE becomes
4.8V or below, and with V_IHM (=3.5V), the equation ⑥ is also satisfied.
・V_OHE : EEPROM V_OH specifications
・I_OHE : EEPROM I_OH specifications
・V_IHM : 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 (Min.200ns)
from CS fall after write command input, “H” or “L” output.
R/B display＝“L” (BUSY) = write under execution
（DO status） After the timer circuit in the IC works and creates the period of t_E/W, this time circuit completes automatically.
And write to the memory cell is made in the period of t_E/W, and during this period, other command is not
accepted.
R/B display = “H” (READY) = command wait status
（DO status） Even after t_E/W (Max.4ms) from write of the memory cell, the following command is accepted.
Therefore, CS=“H” in the period of t_E/W, and when input is in SK, DI, malfunction may occur, Therefore, set
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 canceled, but command input in READY area is accepted.
Therefore, status READY output is canceled, and malfunction and mistake write may be made.
CS
STATUS
SK
CLOCK
DI
WRITE
INSTRUCTION
High-Z
tSV
DO
READY
BUSY
Figure 44. R/B Status Output Timing Chart
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TSZ22111・15・001
18/29
TSZ02201-0R1R0G100030-1-2
19.DEC.2012 Rev.002