MC33989PEG Freescale Semiconductor, MC33989PEG Datasheet - Page 55

• Manufacturer Part Number: MC33989PEG
• Description: SBC-HS
• Manufacturer: Freescale Semiconductor

Table 35. Current in Case of Bus Short Conditions
Notes
MCU increases its TEC «transmit error counter» by 8.The sender node keeps driving TX in dominant until it reaches the error
passive level (TEC=128).
only 1 dominant bit, and as nothing is received on RX, the TEC is incremental by 8. After TX is driven 15 times, the TEC reaches
255: then the node is in the BUS OFF state.
recover and be able to transmit again.
Analog Integrated Circuit Device Data
Freescale Semiconductor
34.
No failure
CANH line to GND
CANH line to 5.0 V
CANH line to +VBAT
CANL line to GND
CANL line to 5.0 V
CANL line to VBAT
CANH line shorted to
CANL line
The sender node drives TX and the CAN bus, but doesn’t receive anything on RX, so the CAN protocol handler inside the
When it is in error passive, it sends a passive error frame (23 bits in recessive). Then the sender nodes drive the bus and send
When the node is in the BUS OFF state, it needs 128 occurrences of 11 recessive bits (1.408 ms at 1.0 MBauds) in order to
For the failure case which leads to loss of communication and current flow for a very short time period as illustrated in
instance for CANH to gnd, the impact of the peak current on the V2 voltage regulator is very limited. The TX, RX, and CAN signal in the
figure are placed in a CANH to CANL short-circuit condition.
Condition
current
I term
150
32
55
50
0
0
0
0
peak current (mA)
current
-150
I_H
150
-55
Figure 45. CANH to CANL Short Circuit Condition
70
0
0
0
0
current
-150
-240
-70
I-L
50
0
0
0
0
Normal communication.
No communication. Current flowing from V2 pin, during CAN driver dominant
state.
communication OK.
communication OK.
communication OK.
no communication
no communication
no communication
(34)
(34)
(34)
(34)
Comment
SUPPLEMENTAL APPLICATION NOTES
TYPICAL APPLICATIONS
Figure
45. So for
33989
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