BR24C21FV Ver la hoja de datos (PDF) - ROHM Semiconductor
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BR24C21FV Datasheet PDF : 21 Pages
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BR24C21xxx Series (1K)
Datasheet
●Command Cancellation By Start And Stop Condition
During a command input, command is canceled by the successive inputs of start condition and stop condition (Figure 15.).
However, during ACK or data output, the device may output the SDA line Low. In such cases, operation of start and stop
condition is impossible, making the reset inoperable. Execute the software reset in the cases. (Figure 13.)
Operating the command cancel by start and stop condition during the command of Random Read or Sequential Read or
Current Read, internal address counter is not confirmed. Therefore operation of Current Read after this is not valid. Operate
a Random Read in this case.
SCL
SDA
1
0
1
0
Start
Condition
Figure 15. Command Cancellation
Stop
Condition
●I/O Circuit
○SDA Pin Pull-up Resister
The pull up resister is needed because SDA is NMOS open drain. Choose the correct value of this resister(RPU), by
considering VIL, IL characteristics of a controller which control the device and VOH, IOL characteristics of the device. If
large RPU is chosen, clock frequency needs to be slow. In case of small RPU, the operating current increases.
○Maximum Rpu
Maximum value of RPU is determined by following factors:
①SDA rise time determined by RPU and the capacitance of bus line(CBUS) must be less than tR.
1)
Other timing must keep the conditions of AC spec.
②When SDA bus is High, the voltage ○A of SDA bus determined by a total input leak(IL) of the all devices connected to
the bus. RPU must be significantly higher than the High level input of a controller and the device, including a noise
margin 0.2VCC.
VCC-ILRPU-0.2 VCC ≧ VIH
MICRO
0.8Vcc-VIH
∴ RPU
≦
IL
COMPUTER
RPU
A
SDA PIN
Examples: When VCC=3V
According to ②
RPU
≦
IL=10µA VIH=0.7VCC
0.8x3-0.7x3
10x10-6
≦ 300 [kΩ]
IL
IL
THE CAPACITANCE OF
BUS LINE (CBUS)
Figure 16. I/O Circuits
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© 2012 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
9/18
TSZ02201-0R2R0G100270-1-2
10.Jul.2012 Rev.001
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