CAN Board - Datasheet

SN65HVD230
SN65HVD231
SN65HVD232
SLOS346G MARCH 2001 REVISED JUNE 2002
22
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APPLICATION INFORMATION
high-speed (continued)
1
1 Mbps
Driver Output
NRZ Data
Figure 31. Typical High Speed SN65HVD230 Output Waveform Into a 60- Load
slope control
Electromagnetic compatibility is essential in many applications using unshielded bus cable to reduce system
cost. To reduce the electromagnetic interference generated by fast rise times and resulting harmonics, the rise
and fall slopes of the SN65HVD230 and SN65HVD231 driver outputs can be adjusted by connecting a resistor
from R
S
(pin 8) to ground or to a logic low voltage, as shown in Figure 32. The slope of the driver output signal
is proportional to the pins output current. This slope control is implemented with an external resistor value of
10 k to achieve a 15 V/µs slew rate, and up to 100 k to achieve a 2.0 V/µs slew rate as displayed in
Figure 33. Typical driver output waveforms from a pulse input signal with and without slope control are displayed
in Figure 34. A pulse input is used rather than NRZ data to clearly display the actual slew rate.
TMS320LF2406
or
TMS320LF2407
IOPF6
1
2
3
4
8
7
6
5
D
GND
V
CC
R
CANH
CANL
V
ref
10 k
to
100 k
R
S
Figure 32. Slope Control/Standby Connection to a DSP