VP232 datasheet(20/32 Pages) TI

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OPERATING MODES

High-Speed

TMS320LF2406

TMS320LF2407

IOPF6

GND

VCC

CANH

CANL

Vref

1 Mbps

Driver Output

NRZ Data

SN65HVD230

SN65HVD231

SN65HVD232

SLOS346H – MARCH 2001 – REVISED JULY 2006

APPLICATION INFORMATION (continued)

The bus pins are also maintained in a high-impedance state during low VCC conditions to ensure glitch-free

power-up and power-down bus protection for hot-plugging applications. This high-impedance condition also

means that an unpowered node does not disturb the bus. Transceivers without this feature usually have a very

low output impedance. This results in a high current demand when the transceiver is unpowered, a condition

that could affect the entire bus.

RS (pin 8) of the SN65HVD230 and SN65HVD231 provides for three different modes of operation: high-speed

mode, slope-control mode, and low-power mode.

The high-speed mode can be selected by applying a logic low to RS (pin 8). The high-speed mode of operation

is commonly employed in industrial applications. High-speed allows the output to switch as fast as possible with

no internal limitation on the output rise and fall slopes. The only limitations of the high-speed operation are cable

length and radiated emission concerns, each of which is addressed by the slope control mode of operation.

If the low-power standby mode is to be employed in the circuit, direct connection to a DSP output pin can be

used to switch between a logic-low level (< 1 V) for high speed operation, and the logic-high level (> 0.75 VCC)

for standby. Figure 34 shows a typical DSP connection, and Figure 35 shows the HVD230 driver output signal in

high-speed mode on the CAN bus.

Figure 34. RS (Pin 8) Connection to a TMS320LF2406/07 for High Speed/Standby Operation

Figure 35. Typical High Speed SN65HVD230 Output Waveform Into a 60-

Ω Load

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