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Slope Control

TMS320LF2406

or

TMS320LF2407

IOPF6

1

2

3

4

8

7

6

5

D

GND

R

CANH

CANL

10 k

Ω

to

100 k

Ω

Slope Control Resistance – k

Ω

0

5

10

15

20

25

0

10

20

30

40

50

60

70

80

90

DRIVER OUTPUT SIGNAL SLOPE

vs

SLOPE CONTROL RESISTANCE

4.7

0

6.8

10

15

22

33

47

68

100

SN65HVD230

SN65HVD231

SN65HVD232

SLOS346H – MARCH 2001 – REVISED JULY 2006

APPLICATION INFORMATION (continued)

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

proportional to the pin's output current. This slope control is implemented with an external resistor value of 10

k

Ω to achieve a ≈ 15 V/µs slew rate, and up to 100 kΩ to achieve a ≈ 2.0 V/µs slew rate as displayed in

Figure 37. Typical driver output waveforms from a pulse input signal with and without slope control are displayed

in Figure 38. A pulse input is used rather than NRZ data to clearly display the actual slew rate.

Figure 36. Slope Control/Standby Connection to a DSP

Figure 37. HVD230 Driver Output Signal Slope vs Slope Control Resistance Value

21

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