P82B96TD,112 NXP Semiconductors, P82B96TD,112 Datasheet - Page 21

• Manufacturer Part Number: P82B96TD,112
• Description: IC I2C BUS BUFFER DUAL 8-SOIC
• Manufacturer: NXP Semiconductors
• Type: Bufferr

Specifications of P82B96TD,112

• Package / Case: 8-SOIC (3.9mm Width)
• Tx/rx Type: I²C Logic
• Delay Time: 5.0ns
• Capacitance - Input: 7pF
• Voltage - Supply: 2 V ~ 15 V
• Current - Supply: 900µA
• Mounting Type: Surface Mount
• Logic Family: P82B
• Supply Voltage (max): 15 V
• Supply Voltage (min): 2 V
• Maximum Operating Temperature: 85 C
• Mounting Style: SMD/SMT
• Maximum Power Dissipation: 300 mW
• Minimum Operating Temperature: - 40 C
• Number Of Lines (input / Output): 4 / 2
• Propagation Delay Time: 90 ns
• Logic Type: Bus Buffer
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: OM6285 - EVAL BOARD I2C-2002-1A568-4002 - DEMO BOARD I2C
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 568-3982-5; 935262295112; P82B96TD; P82B96TD

NXP Semiconductors
P82B96_8
Product data sheet
Fig 23. Wiring transients limited by the diodes in P82B96
Question: We have 2 meters of cable in a bus that joins the Tx/Rx sides of two P82B96
devices. When one Tx drives LOW the other P82B96 Tx/Rx is driven to 0.8 V for over
50 ns. What is the expected value and the theoretically allowed value of undershoot?
Answer: Because the cable joining the two P82B96s is a ‘transmission line’ that will
have a characteristic impedance around 100
resistors that are larger than that characteristic impedance there will always be negative
undershoot generated. The duration of the undershoot is a function of the cable length
and the input impedance of the connected IC. As shown in
undershoot will be limited, by the diodes inside P82B96, to around 0.8 V and that will
not cause problems for P82B96. Those transients will not be passed inside the IC to the
Sx/Sy side of the IC.
Question: If we input 800 mV undershoot at Tx, Rx pins, what kind of problem is
expected?
Answer: When that undershoot is generated by another P82B96 and is simply the
result of the system wiring, then there will be no problems.
Question: Will we have any functional problem or reliability problem?
Answer: No.
voltage
Rev. 08 — 10 November 2009
(V)
Sx
6
4
2
0
2
5 V
horizontal scale = 62.5 ns/div
P82B96
Rx
Tx
send
send
5 V
300
2 meter
cable
receive
and it will be terminated by pull-up
5 V
300
receive
GND
time (ns)
Dual bidirectional bus buffer
Figure
Rx
Tx
002aaf065
5 V
Sx
23, the transient
© NXP B.V. 2009. All rights reserved.
P82B96
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