BR35H160-WC ROHM Co. Ltd., BR35H160-WC Datasheet - Page 11

• Manufacturer Part Number: BR35H160-WC
• Description: Automotive Serial Eeproms
• Manufacturer: ROHM Co. Ltd.

●High speed operations
© 2011 ROHM Co., Ltd. All rights reserved.
BR35H□□□-WC Series
www.rohm.com
In order to realize stable high speed operations, pay attention to the following input / output pin conditions.
○Input pin pull up, pull down resistance
○Pull up resistance
○Pull down resistance
○SO load capacitance condition
○Other cautions
“L” output
Microcontroll
Microcontroll
When attaching pull up, pull down resistance to the EEPROM input pin, select an appropriate value for the
microcontroller VOL, IOL from the VIL characteristics of this IC.
Also, in order to prevent malfunction or erroneous write at power ON/OFF, be sure to make CSB pull up.
The operations speed changes according to the amplitude VIHE, VILE of the signals input to the EEPROM. More stable
high speed operations can be realized by inputting signals with Vcc / GND levels of amplitude. On the contrary, when
signals with an amplitude of 0.8Vcc / 0.2Vcc are input, operation speed slows down.
In order to realize more stable high speed operation, it is recommended to set the values of R
and to have the amplitude of the signals input to the EEPROM close to the Vcc / GND amplitude level.
(
The load capacitance of the SO output pin affects the SO output delay characteristic. (Data output delay time, time from
HOLDB to High-Z, output rise time, output fall time.). Make the SO load capacitance small to improve the output delay
characteristic.
Make all wires from the microcontroller to EEPROM input pin the same length. This in order to prevent setup / hold
violation to the EEPROM.
“H” output
*
1 In this case, the guaranteed value of operating timing is guaranteed.)
V
V
OLM
Fig.44 Pull up resistance
OHM
Fig.45 Pull down resistance
I
OLM
I
OHM
R
R
PD
PU
Fig.46 SO load dependency of data output delay time tPD
“L” input
EEPROM
EEPROM
“H” input
V
V
ILE
IHE
EEPROM
With the value of Rpu to satisfy the above equation, V
becomes 0.4V or lower, and with V
also satisfied.
Example) When Vcc=5V, V
SO
11/16
Example) When V
∴R
R
V
R
OLM
PU
PU
PU
≥
≧
≧
・V
・V
・I
from the equation ①,
V
≤
IHE
∴R
CL
OLM
ILE
OLM
R
V
R
=V
OHM
PD
PD
PU
CC
:Microcontroller V
:EEPROM V
:Microcontroller I
≧
≧
≧
V
V
2.3[kΩ]
≧
×0.7V, from the equation③,
CC
ILE
5－0.4
2×10
I
CC
OLM
-V
=5V, V
OLM
-3
ILE
0.4×10
11.3[kΩ]
V
5－0.5
ILE
I
V
OHM
OHM
=1.5V, V
IHE
IL
(=1.5V), the equation ② is
OHM
specifications
*1
-3
=V
OL
OL
･･･①
･･･②
CC
specifications
OLM
specifications
-0.5V, I
=0.4V, I
PU
･･･③
･･･④
, R
OHM
PD
OLM
Technical Note
2011.03 - Rev.C
＝0.4mA,
as large as possible,
=2mA,
OLM