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Two LEDs are embedded into the connector to report link status (green LED) and transmit and receive
status of the PHY (yellow LED).
2.2.3 CAN Interface
The RM46L852 has up to three DCAN interfaces that provide a high-speed serial interface. Two 3-pin
screw terminal blocks, J2, J3, are used to interface to the DCAN bus. The pinouts for this connector are
shown in
Figure
2-4. H means CAN High (CAN H), and L means CAN Low (CAN L).
CAN Bus termination is used to minimize signal reflection on the bus. ISO-11898 requires that the CAN
bus have a nominal characteristic line impedance of 120 Ω. Therefore, the typical terminating resistor
value for each end of the bus is 120 Ω. A split termination method is used to help increase EMC
performance. Split termination is a concept that is growing in popularity because emission reduction can
be achieved very easily. Split termination is a modified standard termination in which the single 120 Ω
resistor on each end of the bus is split into two 60 Ω resistors, with a bypass capacitor tied between the
resistors and to ground. The two resistors should match as close as possible.
SPNU566A – September 2012 – Revised September 2013
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Table 2-3. J1, Ethernet Interface
Pin Number
Signal
1
D0+
3
D1-
5
D2-
7
D3+
Figure 2-3. CAN Bus Termination
J2
H L
Figure 2-4. J2, J3 CAN Bus Interface (Screw Terminal)
Copyright © 2012–2013, Texas Instruments Incorporated
Pin Number
Signal
2
D0-
4
D2+
6
D1-
8
D3-
H L
Connectors
J3
Physical Description
11
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