Datasheet

PCA9600 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 5 — 5 May 2011 22 of 31
NXP Semiconductors
PCA9600
Dual bidirectional bus buffer
Question: If we add 100 Ω to 200 Ω at signal line, the overshoot becomes slightly
smaller. Is this a good idea?
Answer: No, it is not necessary to add any resistance. When the logic signal generated
by TX or TY of PCA9600 drives long traces or wiring with ICs other than PCA9600
being driven, then adding a Schottky diode (BAT54A) as shown in Figure 25
will clamp
the wiring undershoot to a value that will not cause conduction of the IC’s internal
diodes.
Fig 25. Wiring transients limited by a Schottky diode
002aaf083
time (ns)
2
0
4
6
voltage
(V)
−2
horizontal scale = 62.5 ns/div
receive
5 V
RX
TX
SX
PCA9600
send
300 Ω
5 V
2 meter
cable
5 V
300 Ω
GND
receive
SX
RX
TX
5 V
send
1
/
2
BAT54A